staging: wfx: fix access to le32 attribute 'len'

staging: wfx: fix access to le32 attribute 'len'

Sparse complains about the accesses to the field 'len' from struct hif_msg:

    drivers/staging/wfx/bh.c:88:32: warning: restricted __le16 degrades to integer
    drivers/staging/wfx/bh.c:88:32: warning: restricted __le16 degrades to integer
    drivers/staging/wfx/bh.c:93:32: warning: restricted __le16 degrades to integer
    drivers/staging/wfx/bh.c:93:32: warning: cast to restricted __le16
    drivers/staging/wfx/bh.c:93:32: warning: restricted __le16 degrades to integer
    drivers/staging/wfx/bh.c:121:25: warning: incorrect type in argument 2 (different base types)
    drivers/staging/wfx/bh.c:121:25:    expected unsigned int len
    drivers/staging/wfx/bh.c:121:25:    got restricted __le16 [usertype] len
    drivers/staging/wfx/hif_rx.c:27:22: warning: restricted __le16 degrades to integer
    drivers/staging/wfx/hif_rx.c:347:39: warning: incorrect type in argument 7 (different base types)
    drivers/staging/wfx/hif_rx.c:347:39:    expected unsigned int [usertype] len
    drivers/staging/wfx/hif_rx.c:347:39:    got restricted __le16 const [usertype] len
    drivers/staging/wfx/hif_rx.c:365:39: warning: incorrect type in argument 7 (different base types)
    drivers/staging/wfx/hif_rx.c:365:39:    expected unsigned int [usertype] len
    drivers/staging/wfx/hif_rx.c:365:39:    got restricted __le16 const [usertype] len
    drivers/staging/wfx/./traces.h:195:1: warning: incorrect type in assignment (different base types)
    drivers/staging/wfx/./traces.h:195:1:    expected int msg_len
    drivers/staging/wfx/./traces.h:195:1:    got restricted __le16 const [usertype] len
    drivers/staging/wfx/./traces.h:195:1: warning: incorrect type in assignment (different base types)
    drivers/staging/wfx/./traces.h:195:1:    expected int msg_len
    drivers/staging/wfx/./traces.h:195:1:    got restricted __le16 const [usertype] len
    drivers/staging/wfx/debug.c:319:20: warning: restricted __le16 degrades to integer
    drivers/staging/wfx/secure_link.c:85:27: warning: restricted __le16 degrades to integer
    drivers/staging/wfx/secure_link.c:85:27: warning: restricted __le16 degrades to integer

Indeed, the attribute len is little-endian. We have to take to the
endianness when we access it.

Signed-off-by: Jérôme Pouiller <jerome.pouiller@silabs.com>
Link: https://lore.kernel.org/r/20200512150414.267198-14-Jerome.Pouiller@silabs.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>