ARM: dts: qcom: adapt to LP855X bindings changes

Change underscores in ROM node names to dashes, and remove deprecated
pwm-period property.

Signed-off-by: Artur Weber <aweber.kernel@gmail.com>
Reviewed-by: Luca Weiss <luca@z3ntu.xyz>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20230519180728.2281-4-aweber.kernel@gmail.com