drivers/dma: STM32: Initialising DMA_InitStruct with 0 for stm32l5xx
drivers/dma: STM32: Initialising DMA_InitStruct with 0 for stm32l5xx

In stm32l5xx soc, the LL_DMA_InitTypeDef has 2 more fields
(DoubleBufferMode and TargetMemInDoubleBufferMode) that must be
initialised with 0 else the configuration is wrong and gives
wrong values to the LL_DMA_Init function. Due to this the test
tests/drivers/dma/loop_transfer too would fail.

Signed-off-by: Krishna Mohan Dani <2f92acbcef6b57b10df043e51f4a57d8454f58b9@hcl.com>

finikorg/zephyr,galak/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,finikorg/zephyr,finikorg/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,finikorg/zephyr,finikorg/zephyr,galak/zephyr,zephyrproject-rtos/zephyr