makefiles: remove unnecessary evaluations of PORT variable.

Remove instances of `:=` and export that were causing $(PORT) to
be evaluated where it was not needed.

This is needed for an incoming change that will verify if port is
not set.

Author: jcarrano

boards/cc2538dk/Makefile.include

@@ -23,11 +23,11 @@ export RESET = $(RIOTBOARD)/$(BOARD)/dist/reset.sh
 export PROGRAMMER ?= cc2538-bsl
 
 ifeq ($(PROGRAMMER),cc2538-bsl)
-  export FLASHER = $(RIOTTOOLS)/cc2538-bsl/cc2538-bsl.py
-  export FFLAGS  = -p "$(PORT)" -e -w -v $(HEXFILE)
+  FLASHER = $(RIOTTOOLS)/cc2538-bsl/cc2538-bsl.py
+  FFLAGS  = -p "$(PORT)" -e -w -v $(HEXFILE)
 else ifeq ($(PROGRAMMER),jlink)
-  export FLASHER = $(RIOTBOARD)/$(BOARD)/dist/flash.sh
-  export FFLAGS  = $(BINDIR) $(HEXFILE)
+  FLASHER = $(RIOTBOARD)/$(BOARD)/dist/flash.sh
+  FFLAGS  = $(BINDIR) $(HEXFILE)
 endif
 
 OFLAGS = --gap-fill 0xff

makefiles/murdock.inc.mk

@@ -3,7 +3,7 @@
 #
 
 # (HACK) get actual flash binary from FFLAGS.
-FLASHFILE:=$(filter $(HEXFILE) $(ELFFILE:.elf=.bin) $(ELFFILE),$(FFLAGS))
+FLASHFILE = $(filter $(HEXFILE) $(ELFFILE:.elf=.bin) $(ELFFILE),$(FFLAGS))
 
 #
 # This target will run "make test" on the CI cluster.

makefiles/vars.inc.mk

@@ -69,7 +69,7 @@ export WERROR                # Treat all compiler warnings as errors if set to 1
 export GITCACHE              # path to git-cache executable
 export GIT_CACHE_DIR         # path to git-cache cache directory
 export FLASHER               # The command to call on "make flash".
-export FFLAGS                # The parameters to supply to FLASHER.
+# FFLAGS                	 # The parameters to supply to FLASHER.
 export FLASH_ADDR            # Define an offset to flash code into ROM memory.
 # TERMPROG                   # The command to call on "make term".
 # TERMFLAGS                  # Additional parameters to supply to TERMPROG.