soc: qcom: memory_dump: fix register dump table entry failed

The dump table entry register function will not check the entry ID
is registered or not, so the registration will fail when the table
is full.

This issue was found when continuously load/unload wlan driver.

Change-Id: I977c2efe1fda7544262f2992fb9720b456303a5e
Signed-off-by: Miaoqing Pan <quic_miaoqing@quicinc.com>