powerpc: Replace __ASSEMBLY__ with __ASSEMBLER__ in non-uapi headers

While the GCC and Clang compilers already define __ASSEMBLER__
automatically when compiling assembler code, __ASSEMBLY__ is a
macro that only gets defined by the Makefiles in the kernel.
This is bad since macros starting with two underscores are names
that are reserved by the C language. It can also be very confusing
for the developers when switching between userspace and kernelspace
coding, or when dealing with uapi headers that rather should use
__ASSEMBLER__  instead. So let's standardize now on the __ASSEMBLER__
macro that is provided by the compilers.

This is almost a completely mechanical patch (done with a simple
"sed -i" statement), apart from tweaking two comments manually in
arch/powerpc/include/asm/bug.h and arch/powerpc/include/asm/kasan.h
(which did not have proper underscores at the end) and fixing a
checkpatch error about spaces in arch/powerpc/include/asm/spu_csa.h.

Signed-off-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20250801082007.32904-3-thuth@redhat.com

arch/powerpc/include/asm/pgtable.h

@@ -2,7 +2,7 @@
 #ifndef _ASM_POWERPC_PGTABLE_H
 #define _ASM_POWERPC_PGTABLE_H
 
-#ifndef __ASSEMBLY__
+#ifndef __ASSEMBLER__
 #include <linux/mmdebug.h>
 #include <linux/mmzone.h>
 #include <asm/processor.h>		/* For TASK_SIZE */
@@ -12,7 +12,7 @@
 
 struct mm_struct;
 
-#endif /* !__ASSEMBLY__ */
+#endif /* !__ASSEMBLER__ */
 
 #ifdef CONFIG_PPC_BOOK3S
 #include <asm/book3s/pgtable.h>
@@ -39,7 +39,7 @@ struct mm_struct;
 #define PAGE_AGP		(PAGE_KERNEL_NC)
 #define HAVE_PAGE_AGP
 
-#ifndef __ASSEMBLY__
+#ifndef __ASSEMBLER__
 
 #define PFN_PTE_SHIFT		PTE_RPN_SHIFT
 
@@ -214,6 +214,6 @@ static inline bool arch_supports_memmap_on_memory(unsigned long vmemmap_size)
 
 #endif /* CONFIG_PPC64 */
 
-#endif /* __ASSEMBLY__ */
+#endif /* __ASSEMBLER__ */
 
 #endif /* _ASM_POWERPC_PGTABLE_H */