kbuild: remove redundant $(wildcard ...) for cmd_files calculation

I do not see any reason why $(wildcard ...) needs to be called twice
for computing cmd_files.  Remove the first one.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index 061d0c3..62d5314 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -583,8 +583,7 @@
 # optimization, we don't need to read them if the target does not
 # exist, we will rebuild anyway in that case.
 
-targets := $(wildcard $(sort $(targets)))
-cmd_files := $(wildcard $(foreach f,$(targets),$(dir $(f)).$(notdir $(f)).cmd))
+cmd_files := $(wildcard $(foreach f,$(sort $(targets)),$(dir $(f)).$(notdir $(f)).cmd))
 
 ifneq ($(cmd_files),)
   include $(cmd_files)