msm: camera: isp: Fix no reg dump when EPCR is enabled

During second init request of EPCR, number of reg dump
buffers was set to zero causing no reg dump. Add fix to
ensure value is updated to ife ctx when it is non zero.

CRs-Fixed: 2532096, 2532101
Change-Id: Ic16001314522cc5b227fc3c33d899c719fbaeacd
Signed-off-by: Mukund Madhusudan Atre <matre@codeaurora.org>