uboot-imx

syscon: dm: Add a new method to get a regmap from DTS

syscon_regmap_lookup_by_phandle() can be used to get the regmap of a syscon
device from a reference in the DTS. It operates similarly to the linux
version of the namesake function.

Signed-off-by: Jean-Jacques Hiblot <jjhiblot@ti.com>
Reviewed-by: Simon Glass <sjg@chromium.org>