firmware: cs_dsp: FW_CS_DSP_KUNIT_TEST should not select REGMAP

firmware: cs_dsp: FW_CS_DSP_KUNIT_TEST should not select REGMAP

Enabling a (modular) test should not silently enable additional kernel
functionality, as that may increase the attack vector of a product.

Fix this by making FW_CS_DSP_KUNIT_TEST (and FW_CS_DSP_KUNIT_TEST_UTILS)
depend on REGMAP instead of selecting it.

After this, one can safely enable CONFIG_KUNIT_ALL_TESTS=m to build
modules for all appropriate tests for ones system, without pulling in
extra unwanted functionality, while still allowing a tester to manually
enable REGMAP_BUILD and this test suite on a system where REGMAP is not
enabled by default.

Fixes: dd0b6b1f29b92202 ("firmware: cs_dsp: Add KUnit testing of bin file download")
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Link: https://patch.msgid.link/73c81ac85e21f1c5a75b7628d90cbb0e1b4ed0fa.1737833376.git.geert@linux-m68k.org
Signed-off-by: Mark Brown <broonie@kernel.org>