sb/intel/ibexpeak: Copy the sandybridge bootblock.c file

This allows to port C_ENVIRONMENT_BOOTBLOCK to sandybridge separately
from nehalem.

Change-Id: If3c6619cf22d1e2995eb19823b0f3f969d252b3b
Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/33188
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Felix Held <felix-coreboot@felixheld.de>
Reviewed-by: Nico Huber <nico.h@gmx.de>

src/southbridge/intel/ibexpeak/Kconfig

@@ -53,7 +53,7 @@ config DRAM_RESET_GATE_GPIO
 
 config BOOTBLOCK_SOUTHBRIDGE_INIT
 	string
-	default "southbridge/intel/bd82x6x/bootblock.c"
+	default "southbridge/intel/ibexpeak/bootblock.c"
 
 config SERIRQ_CONTINUOUS_MODE
 	bool