soc/intel/pantherlake/romstage: Configure VGA mode 12 monochrome buffer

This commit implements support for the FSP_VGA_MODE12_MONOCHROME
Kconfig option within the Panther Lake romstage code.

By checking for the CONFIG_FSP_VGA_MODE12_MONOCHROME option, we
set the corresponding VGA_INIT_CONTROL_MODE12_MONOCHROME bit in
the FSP_M_CONFIG structure.

This ensures that when a 1-bit-per-pixel framebuffer is used, the
Intel FSP is correctly informed to replicate the data across the
remaining color planes for display, saving 75% of framebuffer memory
in romstage.

Key changes:
- Define the new VGA_INIT_CONTROL_MODE12_MONOCHROME control bit.
- Conditionally set this control bit in setup_vga_mode12_params()
when CONFIG_FSP_VGA_MODE12_MONOCHROME is enabled.

BUG=b:406725440
TEST=Verify VGA text rotation on Google/Felino.

Change-Id: I1dec24bb7ed44ca07babe0aa6886a50952d3faa2
Signed-off-by: Kapil Porwal <kapilporwal@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/90073
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Subrata Banik <subratabanik@google.com>
Reviewed-by: Jérémy Compostella <jeremy.compostella@intel.com>

src/soc/intel/pantherlake/romstage/ux.c

@@ -46,6 +46,8 @@ static void setup_vga_mode12_params(FSP_M_CONFIG *m_cfg, enum ux_locale_msg id)
 	m_cfg->LogoXPosition = (VGA12_WIDTH - img_width) / 2;
 	m_cfg->LogoYPosition = (VGA12_HEIGHT - img_height) / 2;
 	m_cfg->VgaInitControl |= VGA_INIT_CONTROL_MODE12;
+	if (CONFIG(FSP_VGA_MODE12_MONOCHROME))
+		m_cfg->VgaInitControl |= VGA_INIT_CONTROL_MODE12_MONOCHROME;
 }
 
 static bool ux_inform_user_of_operation(const char *name, enum ux_locale_msg id,

src/soc/intel/pantherlake/romstage/ux.h

@@ -12,5 +12,6 @@ bool ux_inform_user_of_poweroff_operation(const char *name, FSPM_UPD *mupd);
 #define VGA_INIT_CONTROL_ENABLE		BIT(0)
 #define VGA_INIT_CONTROL_MODE12		BIT(1)
 #define VGA_INIT_DISABLE_ANIMATION	BIT(4)
+#define VGA_INIT_CONTROL_MODE12_MONOCHROME	BIT(5)
 
 #endif /* _SOC_INTEL_PANTHERLAKE_ROMSTAGE_UX_H_ */