mtd: msm_qpic_nand: Fix compiler warning

The compiler on MDM9x35 reported a compiler warning on this
driver for uninitialized variable.

So initialize the variable to a default value before accessing it.

Change-Id: I9412f292aa2d2839db565d4e4c9f1e20881e521e
Signed-off-by: Pratibhasagar V <pratibha@codeaurora.org>