egl: Fix missing clamping in eglSetDamageRegionKHR

Clamp the x and y co-ordinates of the rectangles.

v2: Clamp width/height after converting to co-ordinates
    (Ilia Merkin)

Signed-off-by: Harish Krupo <harish.krupo.kps@intel.com>
Reviewed-by: Qiang Yu <yuq825@gmail.com>
Reviewed-by: Tapani Pälli <tapani.palli@intel.com>
Reviewed-by: Eric Engestrom <eric.engestrom@intel.com>
(cherry picked from commit fd734608)