mx7ulp_com: fix incorrect select for SPL options

SPL_GPIO_SUPPORT is named SPL_GPIO since commit 83061dbd ("Rename
GPIO_SUPPORT to GPIO"), SPL_MMC_SUPPORT is named SPL_MMC since commit
103c5f18 ("mmc: Rename MMC_SUPPORT to MMC"), SPL_SERIAL_SUPPORT is
named SPL_SERIAL since commit 2a736066 ("serial: Rename
SERIAL_SUPPORT to SERIAL") so let's select the correct Kconfig options.

Fixes: 8b71576f ("mx7ulp_com: add support for SPL")
Cc: Quentin Schulz <foss+uboot@0leil.net>
Signed-off-by: Quentin Schulz <quentin.schulz@theobroma-systems.com>