msm: mdss: initialize pipe to NULL
msm: mdss: initialize pipe to NULL

Initialize the pipe pointer to NULL.
So that even if the selection of pipe from pipe-pool
fails, the function returns NULL instead of an
uninitialized value.

Change-Id: Ib04c0a983cba6ffe9532862bcaf516877e49746a
CRs-Fixed: 524466
Signed-off-by: Manoj Rao <8e3d629b389a351bc9ec544515e25783a6118870@codeaurora.org>

TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas