dmaengine: fsl-edma: add i.mx7ulp edma2 version support

Add edma2 for i.mx7ulp by version v3, since v2 has already
been used by mcf-edma.
The big changes based on v1 are belows:
1. only one dmamux.
2. another clock dma_clk except dmamux clk.
3. 16 independent interrupts instead of only one interrupt for
all channels.

Signed-off-by: Robin Gong <yibin.gong@nxp.com>
Tested-by: Angelo Dureghello <angelo@sysam.it>
Signed-off-by: Vinod Koul <vkoul@kernel.org>