Staging: rtl8712: remove unnecessary 'out of memory' message

This patch fixes checkpatch.pl warning in file usb_ops_linux.c
WARNING : possible unecessary 'out of memory' message

Signed-off-by: Tapasweni Pathak <tapaswenipathak@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>