pageflags: standardize comment inclusion in asm-offsets.h and fix MIPS

Add the ability to pass comments into asm-offsets.h by generating asm
output like

-># comment line

Mips needs this feature to preserve the comments that are in
asm-mips/asm-offsets.h right now.

Then remove the special handling for mips from Kbuild and convert mips to use
the new string to include the comments.

Cc: Ralf Baechle <[email protected]>
Signed-off-by: Christoph Lameter <[email protected]>
Cc: Sam Ravnborg <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

Kbuild

@@ -52,10 +52,10 @@ targets += arch/$(SRCARCH)/kernel/asm-offsets.s
 
 # Default sed regexp - multiline due to syntax constraints
 define sed-y
-	"/^->/{s:^->\([^ ]*\) [\$$#]*\([^ ]*\) \(.*\):#define \1 \2 /* \3 */:; s:->::; p;}"
+	"/^->/{s:->#\(.*\):/* \1 */:; \
+	s:^->\([^ ]*\) [\$$#]*\([^ ]*\) \(.*\):#define \1 \2 /* \3 */:; \
+	s:->::; p;}"
 endef
-# Override default regexp for specific architectures
-sed-$(CONFIG_MIPS) := "/^@@@/{s/^@@@//; s/ \#.*\$$//; p;}"
 
 quiet_cmd_offsets = GEN     $@
 define cmd_offsets