crypto: msm: ota: multiple variable size packet support

This patch provides support of multiple variable size packet
API to the ota_crypto driver.

Furthermore, this patch replaces snprintf with scnprintf
to make pointer manipulation save when display stats.

Change-Id: I56aebd24557dccc547ff86cb8853ace0602b6e50
Acked-by: Chemin Hsieh <cheminh@qti.qualcomm.com>
Signed-off-by: Rohit Vaswani <rvaswani@codeaurora.org>