ASoC: kirkwood: Fix potential NULL dereference

In kirkwood_dma_hw_params() mv_mbus_dram_info() returns NULL if
CONFIG_PLAT_ORION macro is not defined.
Fix this bug by adding NULL check.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Fixes: bb6a40fc ("ASoC: kirkwood: Fix reference to PCM buffer address")
Signed-off-by: Aleksandr Mishin <amishin@t-argos.ru>
Link: https://msgid.link/r/20240328173337.21406-1-amishin@t-argos.ru


Signed-off-by: Mark Brown <broonie@kernel.org>