aac_convert_sgraw2() masks -ENOMEM

Hey,

today, I have run smatch and it reports, that aac_convert_sgraw2() returns -1 instead of -ENOMEM on kmalloc(). This is easy to fix, but nobody tests what aac_convert_sgraw2() returns in aac_build_sgraw2()

Since commit 0b4334473d48 ("[SCSI] aacraid: SCSI dma mapping failure case handling"), aac_build_sgraw2() should have better error propagation in aac_{read,write}_raw_io().

The question is, that if it's intentional (and I hope it's not) or it's just leftover fix?

Nikola