drm/komeda: Fix error: not allocating enough data 1592 vs 1584

drm/komeda: Fix error: not allocating enough data 1592 vs 1584

The patch 5d51f6c0da1b: "drm/komeda: Add writeback support" from May
23, 2019, leads to the following static checker warning:

        drivers/gpu/drm/arm/display/komeda/komeda_wb_connector.c:151 komeda_wb_connector_add()
        error: not allocating enough data 1592 vs 1584

This is a typo which misuse "wb_conn" but which should be "kwb_conn" to
allocate the memory.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: james qian wang (Arm Technology China) <james.qian.wang@arm.com>
Reviewed-by: Ayan Kumar Halder <ayan.halder@arm.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190819080136.10190-1-james.qian.wang@arm.com