arch: syscalls: simplify uapi/kapi directory creation

$(shell ...) expands to empty. There is no need to assign it to _dummy.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>

arch/microblaze/kernel/syscalls/Makefile

@@ -2,8 +2,7 @@
 kapi := arch/$(SRCARCH)/include/generated/asm
 uapi := arch/$(SRCARCH)/include/generated/uapi/asm
 
-_dummy := $(shell [ -d '$(uapi)' ] || mkdir -p '$(uapi)')	\
-	  $(shell [ -d '$(kapi)' ] || mkdir -p '$(kapi)')
+$(shell mkdir -p $(uapi) $(kapi))
 
 syscall := $(src)/syscall.tbl
 syshdr := $(srctree)/scripts/syscallhdr.sh