fix(PeriphDrivers): Corrected SPI driver on RV32 cores

[petejohanson-adi]

Description

Two fixes for using the SPI driver on the RV32 cores found on MAX32690, MAX32655, MAX78000/2:

• Avoid use of memcpy to write/read volatile registers, favoring direct memory access to avoid platform differences. memcpy is discouraged for volatile access, for this very reason.
• Move lock API calls into conditional to avoid their use on RV32.

This has been tested integrated into Zephyr, and fixes test failures there with some data sizes:

Device testing on:

| Platform                    | ID   | Serial device                  |
|-----------------------------|------|--------------------------------|
| max32690evkit/max32690/rv32 |      | /dev/tty.usbmodem0001760024391 |

INFO    - Adding tasks to the queue...
INFO    - Added initial list of jobs to queue
INFO    - Total complete:    9/   9  100%  built (not run):    0, filtered:   63, failed:    0, error:    0
INFO    - 65 test scenarios (65 configurations) selected, 63 configurations filtered (56 by static filter, 7 at runtime).
INFO    - 2 of 2 executed test configurations passed (100.00%), 0 built (not run), 0 failed, 0 errored, with no warnings in 38.47 seconds.
INFO    - 27 of 27 executed test cases passed (100.00%) on 1 out of total 1469 platforms (0.07%).
INFO    - 3 selected test cases not executed: 3 skipped.
INFO    - 2 test configurations executed on platforms, 0 test configurations were only built.

Hardware distribution summary:

| Board                       | ID   |   Counter |   Failures |
|-----------------------------|------|-----------|------------|
| max32690evkit/max32690/rv32 |      |         2 |          0 |
INFO    - Saving reports...
INFO    - Writing JSON report /Users/petejohanson/source/upstream-zephyr-workspace/zephyr/twister-out/twister.json
INFO    - Writing xunit report /Users/petejohanson/source/upstream-zephyr-workspace/zephyr/twister-out/twister.xml...
INFO    - Writing xunit report /Users/petejohanson/source/upstream-zephyr-workspace/zephyr/twister-out/twister_report.xml...
INFO    - Run completed

(which requires a couple Zephyr fixes as well I'll be submitting there)

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