firmware: cs_dsp: avoid large local variables

firmware: cs_dsp: avoid large local variables

Having 1280 bytes of local variables on the stack exceeds the limit
on 32-bit architectures:

drivers/firmware/cirrus/test/cs_dsp_test_bin.c: In function 'bin_patch_mixed_packed_unpacked_random':
drivers/firmware/cirrus/test/cs_dsp_test_bin.c:2097:1: error: the frame size of 1784 bytes is larger than 1024 bytes [-Werror=frame-larger-than=]

Use dynamic allocation for the largest two here.

Fixes: dd0b6b1f29b9 ("firmware: cs_dsp: Add KUnit testing of bin file download")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Richard Fitzgerald <rf@opensource.cirrus.com>
Link: https://patch.msgid.link/20241216121541.3455880-1-arnd@kernel.org
Signed-off-by: Mark Brown <broonie@kernel.org>