stm32mp1: fix a malformed table

Correct a missing pipe character in one of the tables of the stm32mp1
documentation, which caused compilation errors.

Signed-off-by: Joakim Bech <joakim.bech@linaro.org>
Acked-by: Jens Wiklander <jens.wiklander@linaro.org>

building/devices/stm32mp1.rst

@@ -49,7 +49,7 @@ as listed in table below:
 | `STM32MP157D-DK1`      |                                      |
 +------------------------+--------------------------------------+
 | `STM32MP157C-DK2`      | ``PLATFORM=stm32mp1-157C_DK2``       |
-| `STM32MP157F-DK2`      |
+| `STM32MP157F-DK2`      |                                      |
 +------------------------+--------------------------------------+
 | `STM32MP157C-EV1`      | ``PLATFORM=stm32mp1-157C_EV1``       |
 | `STM32MP157F-EV1`      |                                      |