soc/intel/tigerlake: Fix REG_BASE_SIZE

REG_BASE_SIZE is supposed to represent the size of the REGBAR MMIO space
in KiB. It is currently sized at 4MiB, but this is incorrect, EDS Vol. 2
indicates REGBAR is 16MiB in size, therefore update the constant to
reflect this.

Signed-off-by: Tim Wawrzynczak <twawrzynczak@chromium.org>
Change-Id: I0cfbe5b8bb07faa854efd4bf70640daa117f2bb2
Reviewed-on: https://review.coreboot.org/c/coreboot/+/51754
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Furquan Shaikh <furquan@google.com>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>

src/soc/intel/tigerlake/include/soc/iomap.h

@@ -57,7 +57,7 @@
 #define VTVC0_BASE_SIZE		0x1000
 
 #define REG_BASE_ADDRESS	0xfb000000
-#define REG_BASE_SIZE		0x1000
+#define REG_BASE_SIZE		0x4000
 
 #define HPET_BASE_ADDRESS	0xfed00000