ipc-helper.c: reject invalid SOF_MEM_CAPS_* bits

[marc-hb]

Fixes lack of SOF_MEM_CAPS_* input validation found in #8832

[marc-hb]

Unrelated "signal overflow!" failure in https://sof-ci.01.org/sofpr/PR8850/build2957/devicetest/index.html?model=MTLP_RVP_NOCODEC&testcase=check-alsabat-headset-playback-997 on sh-mtlp-rvp-nocodec-06. Everything else green.

1 unrelated suspend/resume failure in https://sof-ci.01.org/sofpr/PR8850/build2958/devicetest/index.html, everything else green.

1 unrelated failure in https://sof-ci.01.org/sof-pr-viewer/#/build/PR8850/build13640869, every other test is green.

12:53:09,629 INFO  - tests/avs/fw_01_base_fw_modules/test_13_updwmix.py::TestUpdwmix::test_01_13_updownmixer_bat_scope[48000Hz_32in32bit_4ch-48000Hz_32in32bit_2ch1]
12:53:09,649 INFO  - [gw0] [100%] FAILED tests/avs/fw_01_base_fw_modules/test_13_updwmix.py::TestUpdwmix::test_01_13_updownmixer_bat_scope[48000Hz_32in32bit_4ch-48000Hz_32in32bit_2ch1]
12:53:09,650 INFO  -
12:53:09,650 INFO  - =================================== FAILURES ===================================
12:53:09,650 INFO  - _ TestUpdwmix.test_01_13_updownmixer_bat_scope[48000Hz_32in32bit_4ch-48000Hz_32in32bit_2ch1] _

[lgirdwood]

Since this is ABI, its better we make it obvious via an inline comment that MAX_BIT needs to be updated for any new MEM_CAPS addition. I would also define MAX_BIT as CAPS_L3 rather than BIT(8) as this makes it even clearer to anyone reading the code.

[marc-hb]

we make it obvious via an inline comment that MAX_BIT needs to be updated for any new MEM_CAPS addition.

Comment added.

I would also define MAX_BIT as CAPS_L3 rather than BIT(8) as this makes it even clearer to anyone reading the code.

I can't do that because I realized v2 12aff94 was buggy, apologies. In v2 I made _MAX equal to the last last valid bit but that is wrong, it would incorrectly reject _MAX + some other BIT. The tests passed anyway because we don't seem to test L3_HEAP.

The comparison must be with the first invalid bit. I confused myself with the name "_MAX", it is a bad name. I just replaced it with _LOWEST_INVALID = max << 1

[marc-hb]

Only suspend/resume failures in CAVS https://sof-ci.01.org/sofpr/PR8850/build2989/devicetest/index.html

ACE https://sof-ci.01.org/sofpr/PR8850/build2988/devicetest/index.html is all green.