Use the generic variants - the implementation is the same.
As a nice side-effect fix the following warnings:

cmpdi2.c: warning: no previous prototype for '__cmpdi2' [-Wmissing-prototypes]
ucmpdi2.c: warning: no previous prototype for '__ucmpdi2' [-Wmissing-prototypes]
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Fixes: 0fcb7085 ("Makefile.extrawarn: turn on missing-prototypes globally")
Reviewed-by: Randy Dunlap <rdunlap@infradead.org>
Tested-by: Randy Dunlap <rdunlap@infradead.org> # build-tested
Reviewed-by: Maciej W. Rozycki <macro@orcam.me.uk>
Tested-by: Maciej W. Rozycki <macro@orcam.me.uk> # build-tested
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Andreas Larsson <andreas@gaisler.com>
Reviewed-by: Andreas Larsson <andreas@gaisler.com>
Tested-by: Andreas Larsson <andreas@gaisler.com>
Signed-off-by: Andreas Larsson <andreas@gaisler.com>
Link: https://lore.kernel.org/r/20240224-sam-fix-sparc32-all-builds-v2-1-1f186603c5c4@ravnborg.org