rockchip: rk3368: increase MAX_MMAP_REGIONS

Current value is 16, count the MAP_REGION calls gets us at least 17,
so increase the max value to 20 to have a bit of a margin.

Signed-off-by: Heiko Stuebner <heiko.stuebner@theobroma-systems.com>
Change-Id: I93d0324f3d483758366e758f8f663545d365e03f
1 file changed