mach-snapdragon: of_fixup: fix property length at writing

mach-snapdragon: of_fixup: fix property length at writing

The length of a property includes '\0' in a string type one, so
the length passed by needs to have that in account, if not,
when getting the property value it will fail because it
has the wrong size.

Signed-off-by: Rui Miguel Silva <rui.silva@linaro.org>
Tested-by: caleb.connolly@linaro.org # db845c
Reviewed-by: Caleb Connolly <caleb.connolly@linaro.org>
Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://lore.kernel.org/r/20250227094911.497219-2-rui.silva@linaro.org
Signed-off-by: Caleb Connolly <caleb.connolly@linaro.org>