Add PATH to linux build options to allow 'mkimage' to be found. Neccessary for arm,blackfin,sh and avr32 in linux-2.6.28

target/linux/Makefile.in.advanced

@@ -190,7 +190,8 @@ LINUX26_MAKE_FLAGS = HOSTCC="$(HOSTCC)" HOSTCFLAGS="$(HOSTCFLAGS)" \
 	INSTALL_MOD_PATH=$(TARGET_DIR) \
 	CROSS_COMPILE=$(KERNEL_CROSS) \
 	LDFLAGS="$(TARGET_LDFLAGS)" \
-	LZMA="$(LZMA)"
+	LZMA="$(LZMA)" \
+	PATH=$(STAGING_DIR)/usr/bin:$(PATH)
 
 # =============================================================================
 # ifneq ($(strip $(LINUX26_VERSION)),$(strip $(LINUX_HEADERS_VERSION)))