soc: qcom: Reset string table index for each dump collection request

Section name should be placed in String table.
Currently, we used static version for string table
index to update subsequent section names.

Due to this string table index keeps on increasing
during every new dump(subsystem restart) request.
This ultimately will result in buffer overflow,
leading to Redzone overwritten.

Hence, as a fix, now reset, this string table
index once dump capture is complete.

Change-Id: Ibc2446ae4011db5291044eacdc1a1119597d862a
Signed-off-by: Jitendra Sharma <shajit@codeaurora.org>