MAINTAINERS: Fix AMD PTDMA DRIVER entry

Remove the bogus leading plus signs from the entry for the AMD PTDMA
driver.

Fixes: fa5d823b ("dmaengine: ptdma: Initial driver for the AMD PTDMA")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/28b7663ebcaf9363324a615129417b24625a7038.1630413650.git.geert+renesas@glider.be


Signed-off-by: Vinod Koul <vkoul@kernel.org>