USB: gadget: f_mass_storage: get rid of DEVICE_ATTR() usage

USB: gadget: f_mass_storage: get rid of DEVICE_ATTR() usage

The last holdout in the drivers/usb/* tree using DEVICE_ATTR() is the
f_mass_storage driver, so move it to use DEVICE_ATTR_RW() instead.  The
mode is overridden in the is_visible callback to set it properly
depending on if this is a cdrom or removable device.

Cc: Felipe Balbi <balbi@kernel.org>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Maxim Devaev <mdevaev@gmail.com>
Cc: Wesley Cheng <quic_wcheng@quicinc.com>
Cc: Neal Liu <neal_liu@aspeedtech.com>
Cc: Roger Quadros <roger.quadros@nokia.com>
Cc: Nikita Yushchenko <nikita.yoush@cogentembedded.com>
Cc: Cai Huoqing <cai.huoqing@linux.dev>
Link: https://lore.kernel.org/r/20220810123656.3637104-1-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>