leds: qcom-lpg: Add support for PMI632 LPG

The PMI632 PMIC contains 5 PWM channels, 3 of which can be used for
LEDs.

For the LED pattern it doesn't have LUT like other PMICs but uses SDAM
instead. This is not currently implemented in the driver but since LPG
works fine without it, add support for the PMIC now.

Signed-off-by: Luca Weiss <luca@z3ntu.xyz>
Acked-by: Pavel Machek <pavel@ucw.cz>
Reviewed-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Signed-off-by: Lee Jones <lee@kernel.org>
Link: https://lore.kernel.org/r/20230414-pmi632-v2-4-98bafa909c36@z3ntu.xyz