linux: ast2750: Disable I3C DMA modified

DMA mode was enabled in
https://gbmc-review.git.corp.google.com/c/meta-gbmc-staging/+/50575

With DMA mode, after a host reboot we observed 2 different issues.
1. Data padded with dummy bytes to make length 4-byte aligned - 9 byte
transfer becomes 12 bytes with padded data.

2. single transfer split along the word boundary and remaining bytes
sent in next transfer withpadding - 9 byte transfer request sent as one
8 byte and on the next transfer the remaining one byte padded to 4 bytes
and first 4 bytes from the next transfer.

Tested: Validated these transfer issues are not observed after
        host reboot.
Google-Bug-Id: b/469805111
Fusion-Link: fusion2/NA
Change-Id: Ib482b2ba6c69ba9f95a177caa30cb73b2680326a
Signed-off-by: Vivekanand Veeracholan <vveerach@google.com>