Source control bits get cleared when doing a DMA from ROM with a non-incrementing source address

[KellanClark]

Build: 0.9.3
Branch: heads/0.9.3
Revision: 1163869
OS: Linux Mint 64-bit
CPU: Core i7-1065G7
GPU: Intel Iris Plus Graphics

Tested using https://github.com/ICanNotThinkOfAGoodUsername/gbastuff/tree/main/dmacnttest

There is a small issue in the code https://github.com/mgba-emu/mgba/blob/master/src/gba/dma.c#L86-L88 where instead of being ignored and internally treated as increment, the source control bits get physically reset. The value read from DMAxCNT_H after the transfer should remain the same as before (minus the enable bit), but this is not the case as of 0.9.3

Expected:

Actual: