stm32mp1: remove STM32MP_UART_PROGRAMMER flag usage in BL32

STM32MP_UART_PROGRAMMER is no more used when compiling BL32 (SP_min).
The boot interface should then be unconditionally checked when setting
the UART console.
This adds 160 bytes of code.

Change-Id: I54dfa85ea1cb3c6e74a6dc35f13730f26bc904f0
Reviewed-on: https://gerrit.st.com/c/mpu/oe/st/tf-a/+/188320


Reviewed-by: CITOOLS <smet-aci-reviews@lists.codex.cro.st.com>
Reviewed-by: Lionel DEBIEVE <lionel.debieve@st.com>
Reviewed-by: CIBUILD <smet-aci-builds@lists.codex.cro.st.com>
Reviewed-by: Yann GAUTIER <yann.gautier@st.com>
Tested-by: Yann GAUTIER <yann.gautier@st.com>