sh: Refactor header include path addition

Shorten the code. No functional change intended.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Tested-by: Randy Dunlap <rdunlap@infradead.org>
Reviewed-by: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Link: https://lore.kernel.org/r/20230219141555.2308306-3-masahiroy@kernel.org
Signed-off-by: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>

Author: masahir0y

arch/sh/Makefile

@@ -145,8 +145,7 @@ cpuincdir-y			+= cpu-common	# Must be last
 
 drivers-y			+= arch/sh/drivers/
 
-cflags-y	+= $(foreach d, $(cpuincdir-y), -I $(srctree)/arch/sh/include/$(d)) \
-		   $(foreach d, $(machdir-y), -I $(srctree)/arch/sh/include/$(d))
+cflags-y	+= $(addprefix -I $(srctree)/arch/sh/include/, $(cpuincdir-y) $(machdir-y))
 
 KBUILD_CFLAGS		+= -pipe $(cflags-y)
 KBUILD_CPPFLAGS		+= $(cflags-y)