kbuild: replace $(if A,A,B) with $(or A,B)

$(or ...) is available since GNU Make 3.81, and useful to shorten the
code in some places.

Covert as follows:

  $(if A,A,B)  -->  $(or A,B)

This patch also converts:

  $(if A, A, B) --> $(or A, B)

Strictly speaking, the latter is not an equivalent conversion because
GNU Make keeps spaces after commas; if A is not empty, $(if A, A, B)
expands to " A", while $(or A, B) expands to "A".

Anyway, preceding spaces are not significant in the code hunks I touched.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>

scripts/Makefile.lib

@@ -111,7 +111,7 @@ subdir-ym	:= $(addprefix $(obj)/,$(subdir-ym))
 modname-multi = $(sort $(foreach m,$(multi-obj-ym),\
 		$(if $(filter $*.o, $(call suffix-search, $m, .o, -objs -y -m)),$(m:.o=))))
 
-__modname = $(if $(modname-multi),$(modname-multi),$(basetarget))
+__modname = $(or $(modname-multi),$(basetarget))
 
 modname = $(subst $(space),:,$(__modname))
 modfile = $(addprefix $(obj)/,$(__modname))
@@ -434,7 +434,7 @@ MKIMAGE := $(srctree)/scripts/mkuboot.sh
 # SRCARCH just happens to match slightly more than ARCH (on sparc), so reduces
 # the number of overrides in arch makefiles
 UIMAGE_ARCH ?= $(SRCARCH)
-UIMAGE_COMPRESSION ?= $(if $(2),$(2),none)
+UIMAGE_COMPRESSION ?= $(or $(2),none)
 UIMAGE_OPTS-y ?=
 UIMAGE_TYPE ?= kernel
 UIMAGE_LOADADDR ?= arch_must_set_this