soc/intel/apollolake: Avoid CONFIG_PCIEX_LENGTH_256MB selection

This patch removes APL SoC selecting CONFIG_PCIEX_LENGTH_256MB Kconfig
as default configuration for CONFIG_SA_PCIEX_LENGTH_MIB is 256MB.

TEST=Able to build and boot APL platform.

Change-Id: I61249f0adff5e03c07a568556e1ff76b27c6d368
Signed-off-by: Subrata Banik <subrata.banik@intel.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/40378
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-by: Pratikkumar V Prajapati <pratikkumar.v.prajapati@intel.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/soc/intel/apollolake/Kconfig

@@ -54,7 +54,6 @@ config CPU_SPECIFIC_OPTIONS
 	select PCIEXP_COMMON_CLOCK
 	select PCIEXP_CLK_PM
 	select PCIEXP_L1_SUB_STATE
-	select PCIEX_LENGTH_256MB
 	select PMC_INVALID_READ_AFTER_WRITE
 	select PMC_GLOBAL_RESET_ENABLE_LOCK
 	select REG_SCRIPT