dmaengine: dw-edma: Add writeq() and readq() for 64 bits architectures

Add writeq() and readq() for 64 bits architures support.

Supporting these two functions will allow the write or the read of eDMA
64 bits registers at once instead of having two consecutive operations.

Also, this improvement will allow the PCI optimization transaction
messages, which will generate a 64 bits message instead of two messages
of 32 bits.

Signed-off-by: Gustavo Pimentel <gustavo.pimentel@synopsys.com>
Link: https://lore.kernel.org/r/3f1120f7c6003b38ec8b851fc68936007c4d9fd8.1613674948.git.gustavo.pimentel@synopsys.com


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