soc/intel/alderlake: Add provision to show pre-boot splash screen

This patch adds the ability to show a pre-boot splash screen on
Meteor Lake systems using FSP-S.

The patch calls into `fsp_convert_bmp_to_gop_blt()` when the
`BMP_LOGO` config is enabled. This function converts a BMP
file to a BLT buffer, which is then used by FSP-S to render the splash
screen.

Additionally, increase the heap size (malloc'able size) upto 512KB
(when BMP_LOGO config is enabled) to accommodate high
resolution logo file.

BUG=b:284799726
TEST=Able to see splash screen while booting google/marasov
with BMP_LOGO config enable.

Signed-off-by: Subrata Banik <subratabanik@google.com>
Change-Id: I9f4d1bc0aa991e784624ca19ba96a259ab8ddfa6
Reviewed-on: https://review.coreboot.org/c/coreboot/+/77233
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Kapil Porwal <kapilporwal@google.com>
Reviewed-by: Eric Lai <eric_lai@quanta.corp-partner.google.com>
diff --git a/src/soc/intel/alderlake/Kconfig b/src/soc/intel/alderlake/Kconfig
index 480eb30..5facb85 100644
--- a/src/soc/intel/alderlake/Kconfig
+++ b/src/soc/intel/alderlake/Kconfig
@@ -216,6 +216,7 @@
 
 config HEAP_SIZE
 	hex
+	default 0x80000 if BMP_LOGO
 	default 0x10000
 
 config GFX_GMA_DEFAULT_MMIO