ARM: multi_v7_defconfig: enable STM32 SPI

Enable the STM32 SPI driver, implemented on STM32MP1 SoC.
Signed-off-by: Amelie Delaunay <amelie.delaunay@st.com>
Signed-off-by: Alexandre Torgue <alexandre.torgue@st.com>

arch/arm/configs/multi_v7_defconfig

@@ -391,6 +391,7 @@ CONFIG_SPI_S3C64XX=m
 CONFIG_SPI_SH_MSIOF=m
 CONFIG_SPI_SH_HSPI=y
 CONFIG_SPI_SIRF=y
+CONFIG_SPI_STM32=m
 CONFIG_SPI_SUN4I=y
 CONFIG_SPI_SUN6I=y
 CONFIG_SPI_TEGRA114=y