arm64: dts: sdm845-mtp: Reserve reserved gpios

With the introduction of 3edfb7bd ("gpiolib: Show correct direction
from the beginning") the gpiolib will attempt to read the direction of
all pins, which triggers a read from protected register regions.

The pins 0 through 3 and 81 through 84 are protected, so mark these as
reserved.

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