drivers: Cleans variable scopes for STM32 drivers

Fix the scope of some variables in various STM32 drivers including:
 - SDMMC
 - DMA
 - OSPI/QSPI Flash
 - Interrupt controller

The variables are set static instead of global and const if appropriate.

Signed-off-by: Guillaume Gautier <guillaume.gautier-ext@st.com>
6 files changed