hikey.mk: update help text for 'make flash'

The EDK2/UEFI welcome message when booting into fastboot mode has
changed since a while ago [1], but we never updated it correspondingly
in our Makefile, so do it now.

LINK: [1] https://github.com/96boards-hikey/edk2/commit/f5d1102d7bf42ede641520c5c228a0e51139a58e


Signed-off-by: Victor Chong <victor.chong@linaro.org>
Signed-off-by: Jerome Forissier <jerome@forissier.org>
Acked-by: Jerome Forissier <jerome@forissier.org>

hikey.mk

@@ -367,7 +367,8 @@ ifneq ($(FROM_RECOVERY),1)
 	@echo
 	$(call flash_help)
 	@echo "3. Wait until you see the (UART) message"
-	@echo "    \"Android Fastboot mode - version x.x Press any key to quit.\""
+	@echo "    \"Android Fastboot mode - version x.x.\""
+	@echo "     Press RETURN or SPACE key to quit.\""
 endif
 	@read -r -p "Then press enter to continue flashing" dummy
 	@echo