soc: qcom: memory_dump: fix the end address passed to dmac_flush_range()

Fix the pointer arithmetic to ensure the end address passed in
dmac_flush_range() call doesn't go beyond the end of the
msm_dump_table.

Change-Id: I95e7ae8d1b21e1aa6f3aacb34555dc38dd8ab27b
Signed-off-by: Pratik Patel <pratikp@codeaurora.org>