mb/gigabyte/ga-g41m-es2l: Add MAX_CPU = 4 in Kconfig

This motherboard support Intel core 2 quads.

Before this change SeaBIOS was not usable, due to it crashing before it
got to load anything.

Change-Id: Ifdaaceace04f9ba0753aab2d3b05c0519367f91f
Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-on: https://review.coreboot.org/17537
Tested-by: build bot (Jenkins)
Reviewed-by: Kyösti Mälkki <kyosti.malkki@gmail.com>

src/mainboard/gigabyte/ga-g41m-es2l/Kconfig

@@ -46,4 +46,8 @@ config MAINBOARD_PART_NUMBER
 	string
 	default "GA-G41M-ES2L"
 
+config MAX_CPUS
+	int
+	default 4
+
 endif # BOARD_GIGABYTE_GA_G41M_ES2L