x86: Fix CONFIG_X86_GRUB_SERIAL=""

With

    .config:CONFIG_X86_GRUB_SERIAL=""

which (AFAICT) is the way to tell GRUB not to use a serial console, in

    target/linux/x86/image/Makefile:ifneq ($(CONFIG_X86_GRUB_SERIAL),)

$(CONFIG_X86_GRUB_SERIAL) expands to `""' (a literal double double-quote),
making the condition unconditionally false.

This patch fixes the situation by passing CONFIG_X86_GRUB_SERIAL through
qstrip before testing.

Signed-off-by: Tamas TEVESZ <ice@extreme.hu>

SVN-Revision: 37749

target/linux/x86/image/Makefile

@@ -28,8 +28,10 @@ ifneq ($(CONFIG_X86_GRUB_CONSOLE),)
   GRUB_TERMINALS += console
 endif
 
-ifneq ($(CONFIG_X86_GRUB_SERIAL),)
-  GRUB_CONSOLE_CMDLINE += console=$(call qstrip,$(CONFIG_X86_GRUB_SERIAL)),$(CONFIG_X86_GRUB_BAUDRATE)n8
+GRUB_SERIAL:=$(call qstrip,$(CONFIG_X86_GRUB_SERIAL))
+
+ifneq ($(GRUB_SERIAL),)
+  GRUB_CONSOLE_CMDLINE += console=$(GRUB_SERIAL),$(CONFIG_X86_GRUB_BAUDRATE)n8
   GRUB_SERIAL_CONFIG := serial --unit=0 --speed=$(CONFIG_X86_GRUB_BAUDRATE) --word=8 --parity=no --stop=1
   GRUB_TERMINALS += serial
 endif