fix(PeriphDrivers): Initialize SPI DMA channel states before shutdown

[haluk-k]

Description

Initialize the SPI RevA1 TX and RX DMA channel state fields to
E_NO_DEVICE during static initialization.

The Zephyr MAX32 SPI driver calls MXC_SPI_Shutdown() before the first
SPI initialization. Since the static SPI state array was zero-initialized,
both DMA channel fields initially contained channel 0.

As a result, MXC_SPI_RevA1_Shutdown() treated DMA channel 0 as an
acquired channel and released it. A subsequent SPI DMA transfer attempted
to use the released channel and returned E_BAD_PARAM.

Changes

• Initialize channelTx to E_NO_DEVICE for every SPI instance
• Initialize channelRx to E_NO_DEVICE for every SPI instance
• Preserve the existing initialization and shutdown behavior

Root Cause

The default zero initialization of the static SPI state array represents a
valid DMA channel number. However, before MXC_SPI_RevA1_InitState() is
called, no DMA channel has actually been acquired by the SPI driver.

Calling shutdown during this state therefore releases DMA channel 0
incorrectly.

Expected Result

The initial SPI shutdown does not release DMA channel 0 unless the SPI
driver previously acquired it. SPI DMA transfers can subsequently use the
configured DMA channels without returning E_BAD_PARAM.

[haluk-k]

Hi @ttmut , could you please take a look at this PR? I wasn't able to assign you as a reviewer. Thanks!

[ttmut]

Hi @haluk-k, I believe this is not necessary anymore since zephyrproject-rtos/zephyr@eeef2b9

[haluk-k]

Hi @ttmut, I think the change you mentioned will solve the problem. Therefore, I will close this PR, since it seems to be unnecessary.