msm: mdss: rely on client provided stride for CWB

Though CWB output is configured to primary resolution,
client can provide an output buffer with bigger stride.
Use client stride for computing output buffer plane info.

Change-Id: Ib632c95fbb89dc181247dddee27b393a65aaa296
Signed-off-by: Prabhanjan Kandula <pkandula@codeaurora.org>