kbuild: consolidate redundant sed script ASM offset generation

This part ended up in redundant code after touched by multiple
people.

[1] Commit 3234282f33 ("x86, asm: Fix CFI macro invocations to
deal with shortcomings in gas") added parentheses for defined
expressions to support old gas for x86.

[2] Commit a22dcdb003 ("x86, asm: Fix ancient-GAS workaround")
split the pattern into two to avoid parentheses for non-numeric
expressions.

[3] Commit 95a2f6f72d ("Partially revert patch that encloses
asm-offset.h numbers in brackets") removed parentheses from numeric
expressions as well because parentheses in MN10300 assembly have a
special meaning (pointer access).

Apparently, there is a conflict between [1] and [3].  After all,
[3] took precedence, and a long time has passed since then.

Now, merge the two patterns again because the first one is covered
by the other.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Matthias Kaehlcke <mka@chromium.org>

scripts/Makefile.lib

@@ -415,7 +415,6 @@ cmd_xzmisc = (cat $(filter-out FORCE,$^) | \
 # Default sed regexp - multiline due to syntax constraints
 define sed-offsets
 	"/^->/{s:->#\(.*\):/* \1 */:; \
-	s:^->\([^ ]*\) [\$$#]*\([-0-9]*\) \(.*\):#define \1 \2 /* \3 */:; \
 	s:^->\([^ ]*\) [\$$#]*\([^ ]*\) \(.*\):#define \1 \2 /* \3 */:; \
 	s:->::; p;}"
 endef