dmaengine: tegra210-adma: Fix spelling

Correct spelling of 'register' in Tegra210 ADMA driver.

Fixes: ded1f3db ("dmaengine: tegra210-adma: prepare for supporting newer Tegra chips")

Signed-off-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Vinod Koul <vkoul@kernel.org>