mwl8k: Add missing check after DMA map

mwl8k: Add missing check after DMA map

[ Upstream commit 50459501b9a212dbe7a673727589ee105a8a9954 ]

The DMA map functions can fail and should be tested for errors.
If the mapping fails, unmap and return an error.

Fixes: 788838ebe8a4 ("mwl8k: use pci_unmap_addr{,set}() to keep track of unmap addresses on rx")
Signed-off-by: Thomas Fourier <fourier.thomas@gmail.com>
Link: https://patch.msgid.link/20250709111339.25360-2-fourier.thomas@gmail.com
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>