mtd: msm_qpic_nand: update nand device detection

Instead of using just one byte (device id) of nand id, use the full
four bytes read from nand device to properly identify the nand device.
This will help in the cases where the device id is the same but the
device parameters are not.

Change-Id: Ide2cf55c6e0a542a9d1babc8454050ec98f0de78
Signed-off-by: Krishna Konda <kkonda@codeaurora.org>