arm64: dts: dwc3: description of incr burst type

Add description of 'snps,incr-burst-type-adjustment' to binding
so that configuring devicetree.

Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Ran Wang <ran.wang_1@nxp.com>
Signed-off-by: Pengbo Mu <pengbo.mu@nxp.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>