misc/xilinx_sdfec: Call kunmap() on pages mapped with kmap()

misc/xilinx_sdfec: Call kunmap() on pages mapped with kmap()

Pages in an array are mapped in a loop but, after the code is done with
the virtual addresses, these pages are never unmapped.

Therefore, call kunmap() to unmap pages[i].

Cc: "Venkataramanan, Anirudh" <anirudh.venkataramanan@intel.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>
Link: https://lore.kernel.org/r/20220901154408.23984-2-fmdefrancesco@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>