arm64: dts: imx8mq-librem5: higher boost regulation current

1,5A is what's used by the type-c controller on the Librem 5 board so
increase ti,boost-max-current to 1,5A too.

Signed-off-by: Guido Günther <agx@sigxcpu.org>
Signed-off-by: Martin Kepplinger <martin.kepplinger@puri.sm>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>