dmaengine: loongson2-apb: Rename the prefix ls2x to loongson2

dmaengine: loongson2-apb: Rename the prefix ls2x to loongson2

Since commit e06c43231214 ("dmaengine: Loongson1: Add Loongson-1 APB DMA
driver"), the Loongson-1 dma controller was added.

Unfortunately their naming has not been standardized, as CPUs belonging
to the same Loongson family, we expect to standardize the naming for
ease of understanding.

Signed-off-by: Binbin Zhou <zhoubinbin@loongson.cn>
Link: https://lore.kernel.org/r/20240924064241.2414629-1-zhoubinbin@loongson.cn
Signed-off-by: Vinod Koul <vkoul@kernel.org>