staging: rtl8723au: include/rtl8723a_hal.h: fix Rsvd1 size in fw header struct

The size of field Rsvd1 in struct rt_8723a_firmware_hdr should be u8
otherwise we exceeds the boundaries of "LONG WORD 0". This patch fixes
the issue.

Signed-off-by: Daniele Alessandrelli <daniele.alessandrelli@gmail.com>
Acked-by: Jes Sorensen <Jes.Sorensen@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>