parisc: Replace __ASSEMBLY__ with __ASSEMBLER__ in uapi headers

__ASSEMBLY__ is only defined by the Makefile of the kernel, so
this is not really useful for uapi headers (unless the userspace
Makefile defines it, too). Let's switch to __ASSEMBLER__ which
gets set automatically by the compiler when compiling assembly
code.

This is almost a completely mechanical patch (done with a simple
"sed -i" statement), except for a manual change in the file
arch/parisc/include/uapi/asm/signal.h (where a comment was missing
some underscores).

Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
Cc: Helge Deller <deller@gmx.de>
Cc: linux-parisc@vger.kernel.org
Signed-off-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Helge Deller <deller@gmx.de>