soc/intel/broadwell: Move MAX_CPUS from mb to SoC

All Broadwell boards use 8 for MAX_CPUS, so this option can be factored
out into SoC Kconfig.

Change-Id: I311b95ea75a7c6b76b32c7197a0cec86db644234
Signed-off-by: Felix Singer <felixsinger@posteo.net>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/49122
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-by: Michael Niewöhner <foss@mniewoehner.de>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/mainboard/google/auron/Kconfig

@@ -58,10 +58,6 @@ config EC_GOOGLE_CHROMEEC_BOARDNAME
 	default "samus" if BOARD_GOOGLE_SAMUS
 	default ""
 
-config MAX_CPUS
-	int
-	default 8
-
 config VGA_BIOS_FILE
 	string
 	default "pci8086,0406.rom"

src/mainboard/google/jecht/Kconfig

@@ -39,10 +39,6 @@ config MAINBOARD_PART_NUMBER
 	default "Rikku" if BOARD_GOOGLE_RIKKU
 	default "Tidus" if BOARD_GOOGLE_TIDUS
 
-config MAX_CPUS
-	int
-	default 8
-
 config VGA_BIOS_FILE
 	string
 	default "pci8086,0406.rom"

src/mainboard/intel/wtm2/Kconfig

@@ -25,11 +25,6 @@ config MAINBOARD_PART_NUMBER
 	string
 	default "WHITETIP MOUNTAIN 2"
 
-
-config MAX_CPUS
-	int
-	default 8
-
 config VGA_BIOS_FILE
 	string
 	default "pci8086,0166.rom"

src/mainboard/purism/librem_bdw/Kconfig

@@ -52,10 +52,6 @@ config MAINBOARD_VERSION
 	default "1.0" if BOARD_PURISM_LIBREM13_V1
 	default "2.0" if BOARD_PURISM_LIBREM15_V2
 
-config MAX_CPUS
-	int
-	default 8
-
 config PRE_GRAPHICS_DELAY
 	int
 	default 50

src/soc/intel/broadwell/Kconfig

@@ -39,6 +39,10 @@ config CPU_SPECIFIC_OPTIONS
 	select HAVE_POWER_STATE_AFTER_FAILURE
 	select HAVE_POWER_STATE_PREVIOUS_AFTER_FAILURE
 
+config MAX_CPUS
+	int
+	default 8
+
 config PCIEXP_ASPM
 	bool
 	default y