[SCSI] bsg: add linux/types.h include to bsg.h

Since bsg.h has recently been added to the list of kernel
headers that should be exported to the user space, this
attachment makes bsg.h more user space "friendly".
Specifically autotools dislike headers that don't compile
freestanding and bsg.h's use of __u32 types (and friends)
are not standard C (C90 or C99). The inclusion of
linux/types.h fixes that.

Signed-off-by: Douglas Gilbert <dgilbert@interlog.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>