staging: r8188eu: Replace wrapper around _rtw_memcmp()

This wrapper is replaced with a simple memcmp(). As the wrapper inverts the
logic of memcmp(), care needed to be taken.

This patch also adds one include of vmalloc.h that was missed in a previous
patch.

Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>