mmc: dw_mmc-rockchip: switch to FIELD_PREP_WM16 macro

mmc: dw_mmc-rockchip: switch to FIELD_PREP_WM16 macro

The era of hand-rolled HIWORD_UPDATE macros is over, at least for those
drivers that use constant masks.

Switch to the new FIELD_PREP_WM16 macro in hw_bitfield.h, which has
error checking. Instead of redefining the driver's HIWORD_UPDATE macro
in this case, replace the two only instances of it with the new macro,
as I could test that they result in an equivalent value.

Acked-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Nicolas Frattaroli <nicolas.frattaroli@collabora.com>
Reviewed-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Yury Norov (NVIDIA) <yury.norov@gmail.com>