staging: rtl8712: Replace GFP_ATOMIC with GFP_KERNEL

Replace GFP_ATOMIC with GFP_KERNEL since GFP_ATOMIC is used in
atomic context and only needed when functions are not allowed to sleep
whereas the function is later calling msleep().

Signed-off-by: Amitoj Kaur Chawla <amitoj1606@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>