wifi: mt76: Get rid of dma_sync_single_for_device() for MMIO devices

Since the page_pool for MT76 MMIO devices are created with
PP_FLAG_DMA_SYNC_DEV flag, we do not need to sync_for_device each page
received from the pool since it is already done by the page_pool
codebase.

Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Link: https://patch.msgid.link/20250625-mt76-sync-for-device-v1-1-e687e3278e1a@kernel.org


Signed-off-by: Felix Fietkau <nbd@nbd.name>