UAPI: Don't include linux/compat.h in sparc's asm/siginfo.h

Don't include linux/compat.h in sparc's asm/siginfo.h as it leads to a circular
dependency:

	asm/siginfo.h -> linux/compat.h -> asm/siginfo.h

Signed-off-by: David Howells <dhowells@redhat.com>
cc: David S. Miller <davem@davemloft.net>
cc: sparclinux@vger.kernel.org