arm64: dts: qcom: msm8998-mtp: Fix label on l15 regulator

The label on the l15 regulator node does not follow the style of the
rest of the regulator nodes.  Luckily, no one has used the label yet,
so lets fix it.

Fixes: 31c1f0e3 ("arm64: dts: qcom: msm8998: Add RPM and regulators for MTP")
Signed-off-by: Jeffrey Hugo <jeffrey.l.hugo@gmail.com>
Link: https://lore.kernel.org/r/20200528144814.44143-1-jeffrey.l.hugo@gmail.com


Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>