firmware: create firmware binaries during 'make modules'.

This means that we no longer need write access to the source tree while
doing 'make modules_install'.
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

Makefile

@@ -1061,6 +1061,7 @@ modules: $(vmlinux-dirs) $(if $(KBUILD_BUILTIN),vmlinux)
 	$(Q)$(AWK) '!x[$$0]++' $(vmlinux-dirs:%=$(objtree)/%/modules.order) > $(objtree)/modules.order
 	@echo '  Building modules, stage 2.';
 	$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modpost
+	$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.fwinst obj=firmware __fw_modbuild
 
 
 # Target to prepare building external modules

scripts/Makefile.fwinst

@@ -17,14 +17,15 @@ include $(srctree)/$(obj)/Makefile
 
 include scripts/Makefile.host
 
-mod-fw := $(addprefix $(INSTALL_FW_PATH)/,$(fw-shipped-m))
-
+mod-fw := $(fw-shipped-m)
 # If CONFIG_FIRMWARE_IN_KERNEL isn't set, then install the 
 # firmware for in-kernel drivers too.
 ifndef CONFIG_FIRMWARE_IN_KERNEL
-mod-fw += $(addprefix $(INSTALL_FW_PATH)/,$(fw-shipped-y))
+mod-fw += $(fw-shipped-y)
 endif
 
+installed-mod-fw := $(addprefix $(INSTALL_FW_PATH)/,$(mod-fw))
+
 installed-fw := $(addprefix $(INSTALL_FW_PATH)/,$(fw-shipped-all))
 installed-fw-dirs := $(sort $(dir $(installed-fw))) $(INSTALL_FW_PATH)/.
 
@@ -49,7 +50,8 @@ PHONY +=  __fw_install __fw_modinst FORCE
 .PHONY: $(PHONY)
 
 __fw_install: $(installed-fw)
-__fw_modinst: $(mod-fw)
+__fw_modinst: $(installed-mod-fw)
+__fw_modbuild: $(addprefix $(obj)/,$(mod-fw))
 
 FORCE: