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/Makefile b/Makefile
index a7476e6..58dd245 100644
--- a/Makefile
+++ b/Makefile
@@ -1693,8 +1693,7 @@
 
 # read all saved command lines
 
-targets := $(wildcard $(sort $(targets)))
-cmd_files := $(wildcard .*.cmd $(foreach f,$(targets),$(dir $(f)).$(notdir $(f)).cmd))
+cmd_files := $(wildcard .*.cmd $(foreach f,$(sort $(targets)),$(dir $(f)).$(notdir $(f)).cmd))
 
 ifneq ($(cmd_files),)
   $(cmd_files): ;	# Do not try to update included dependency files