soc: qcom: fix to avoid invalid memory access

In error scenarios, tx_buf is accessed even after tx_buf
memory is freed up. This change is to avoid access to freed
up memory.

Change-Id: I93a2c5875474094da1de07ddaaad8a709193632f
Signed-off-by: Vidyakumar Athota <vathota@codeaurora.org>