ARM: configs: Add STM32 defconfig

This patch adds a new config for STM32 MCUs.
STM32F429 Discovery board boots successfully with this config applied.
Tested-by: Chanwoo Choi <cw00.choi@samsung.com>
Signed-off-by: Maxime Coquelin <mcoquelin.stm32@gmail.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

arch/arm/configs/stm32_defconfig

+CONFIG_NO_HZ_IDLE=y
+CONFIG_HIGH_RES_TIMERS=y
+CONFIG_LOG_BUF_SHIFT=16
+CONFIG_BLK_DEV_INITRD=y
+CONFIG_INITRAMFS_SOURCE="./rootfs.cpio"
+CONFIG_CC_OPTIMIZE_FOR_SIZE=y
+# CONFIG_UID16 is not set
+# CONFIG_BASE_FULL is not set
+# CONFIG_FUTEX is not set
+# CONFIG_EPOLL is not set
+# CONFIG_SIGNALFD is not set
+# CONFIG_EVENTFD is not set
+# CONFIG_AIO is not set
+CONFIG_EMBEDDED=y
+# CONFIG_VM_EVENT_COUNTERS is not set
+# CONFIG_SLUB_DEBUG is not set
+# CONFIG_LBDAF is not set
+# CONFIG_BLK_DEV_BSG is not set
+# CONFIG_IOSCHED_DEADLINE is not set
+# CONFIG_IOSCHED_CFQ is not set
+# CONFIG_MMU is not set
+CONFIG_ARCH_STM32=y
+CONFIG_SET_MEM_PARAM=y
+CONFIG_DRAM_BASE=0x90000000
+CONFIG_FLASH_MEM_BASE=0x08000000
+CONFIG_FLASH_SIZE=0x00200000
+CONFIG_PREEMPT=y
+# CONFIG_ATAGS is not set
+CONFIG_ZBOOT_ROM_TEXT=0x0
+CONFIG_ZBOOT_ROM_BSS=0x0
+CONFIG_XIP_KERNEL=y
+CONFIG_XIP_PHYS_ADDR=0x08008000
+CONFIG_BINFMT_FLAT=y
+CONFIG_BINFMT_SHARED_FLAT=y
+# CONFIG_COREDUMP is not set
+CONFIG_DEVTMPFS=y
+CONFIG_DEVTMPFS_MOUNT=y
+# CONFIG_FW_LOADER is not set
+# CONFIG_BLK_DEV is not set
+CONFIG_EEPROM_93CX6=y
+# CONFIG_INPUT is not set
+# CONFIG_SERIO is not set
+# CONFIG_VT is not set
+# CONFIG_UNIX98_PTYS is not set
+# CONFIG_LEGACY_PTYS is not set
+CONFIG_SERIAL_NONSTANDARD=y
+# CONFIG_DEVKMEM is not set
+CONFIG_SERIAL_STM32=y
+CONFIG_SERIAL_STM32_CONSOLE=y
+# CONFIG_HW_RANDOM is not set
+# CONFIG_HWMON is not set
+# CONFIG_USB_SUPPORT is not set
+CONFIG_NEW_LEDS=y
+CONFIG_LEDS_CLASS=y
+CONFIG_LEDS_TRIGGERS=y
+CONFIG_LEDS_TRIGGER_HEARTBEAT=y
+# CONFIG_FILE_LOCKING is not set
+# CONFIG_DNOTIFY is not set
+# CONFIG_INOTIFY_USER is not set
+CONFIG_NLS=y
+CONFIG_PRINTK_TIME=y
+CONFIG_DEBUG_INFO=y
+# CONFIG_ENABLE_WARN_DEPRECATED is not set
+# CONFIG_ENABLE_MUST_CHECK is not set
+CONFIG_MAGIC_SYSRQ=y
+# CONFIG_SCHED_DEBUG is not set
+# CONFIG_DEBUG_BUGVERBOSE is not set
+# CONFIG_FTRACE is not set
+CONFIG_CRC_ITU_T=y
+CONFIG_CRC7=y