configs: stm32mp15_basic: Set regulator relative flags

Enable DM_REGULATOR_STPMU1 flag to activate regulator
driver for STM32MP15 SoC and CMD_REGULATOR flag to be
able to set/get regulator state int U-boot command line.

Disable PMIC_CHILDREN as this flag is not needed in SPL
for STM32MP1.

Signed-off-by: Patrice Chotard <patrice.chotard@st.com>

configs/stm32mp15_basic_defconfig

@@ -23,6 +23,7 @@ CONFIG_CMD_GPT=y
 CONFIG_CMD_I2C=y
 CONFIG_CMD_MMC=y
 CONFIG_CMD_PMIC=y
+CONFIG_CMD_REGULATOR=y
 CONFIG_CMD_EXT4_WRITE=y
 # CONFIG_SPL_DOS_PARTITION is not set
 CONFIG_DM_I2C=y
@@ -31,6 +32,10 @@ CONFIG_DM_MMC=y
 CONFIG_STM32_SDMMC2=y
 # CONFIG_SPL_PINCTRL_FULL is not set
 CONFIG_DM_PMIC=y
+# CONFIG_SPL_PMIC_CHILDREN is not set
 CONFIG_PMIC_STPMU1=y
+CONFIG_DM_REGULATOR=y
+CONFIG_DM_REGULATOR_GPIO=y
+CONFIG_DM_REGULATOR_STPMU1=y
 CONFIG_STM32_SERIAL=y
 # CONFIG_EFI_LOADER is not set