It turns out that the pm660 PON is a GEN2 device.  Update the compatible
to "qcom,pm8998-pon" and add reboot mode support, so that devices can be
rebooted into bootloader and recovery mode.  Tested on Xiaomi Redmi Note
7 phone.

While at it, drop the unnecessary newline between 'compatible' and 'reg'
property.
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@somainline.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20210824021918.17271-1-shawn.guo@linaro.org