drm/komeda: Adds error event print functionality

Adds to print the event message when error happens and the same event
will not be printed until next vsync.

Changes since v2:
1. Refine komeda_sprintf();
2. Not using STR_SZ macro for the string size in komeda_print_events().

Changes since v1:
1. Handling the event print by CONFIG_KOMEDA_ERROR_PRINT;
2. Changing the max string size to 256.

Signed-off-by: Lowry Li (Arm Technology China) <lowry.li@arm.com>
Reviewed-by: Mihail Atanassov <mihail.atanassov@arm.com>
Reviewed-by: James Qian Wang (Arm Technology China) <james.qian.wang@arm.com>
Signed-off-by: james qian wang (Arm Technology China) <james.qian.wang@arm.com>
Link: https://patchwork.freedesktop.org/patch/msgid/1564738954-6101-1-git-send-email-lowry.li@arm.com