soc/intel/common/feature/uart: Add common UART device list driver

This patch introduces a common UART device list implementation that
eliminates duplication across multiple Intel SoC platforms. Instead of
maintaining nearly identical uart.c files in each platform directory,
this common driver uses platform-specific macros to define UART device
function numbers.

The common implementation expects each platform to define the following
macros in their soc/pci_devs.h header:
- PCI_DEVFN_UART0
- PCI_DEVFN_UART1
- PCI_DEVFN_UART2

This approach maintains platform flexibility while reducing code
duplication and simplifying maintenance. The driver is compiled across
all stages (bootblock, verstage, romstage, postcar, ramstage, smm) to
support various UART usage scenarios.

Change-Id: Iba82a2fe24dd9ccf704e4a0fadc481b63662b94d
Signed-off-by: Jeremy Compostella <jeremy.compostella@intel.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/91241
Reviewed-by: Kim, Wonkyu <wonkyu.kim@intel.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Pranava Y N <pranavayn@google.com>

src/soc/intel/common/feature/uart/Kconfig

@@ -0,0 +1,9 @@
+## SPDX-License-Identifier: GPL-2.0-only
+
+config SOC_INTEL_COMMON_FEATURE_UART_DEVICES
+	bool
+	help
+	  Include common UART device list support. This option eliminates
+	  per-platform duplication of uart.c files by providing a common
+	  implementation. Platforms must define PCI_UART_DEVFN* macro in
+	  their soc/pci_devs.h header.

src/soc/intel/common/feature/uart/Makefile.mk

@@ -0,0 +1,3 @@
+## SPDX-License-Identifier: GPL-2.0-only
+all-$(CONFIG_SOC_INTEL_COMMON_FEATURE_UART_DEVICES) += uart_devices.c
+smm-$(CONFIG_SOC_INTEL_COMMON_FEATURE_UART_DEVICES) += uart_devices.c

src/soc/intel/common/feature/uart/uart_devices.c

@@ -0,0 +1,12 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#include <commonlib/helpers.h>
+#include <soc/pci_devs.h>
+
+const unsigned int uart_devices[] = {
+	PCI_DEVFN_UART0,
+	PCI_DEVFN_UART1,
+	PCI_DEVFN_UART2,
+};
+
+const int uart_devices_size = ARRAY_SIZE(uart_devices);