msm: ep-pcie: Fix icc bus vote and add icc bus unvote

We need to perform icc bus vote when enable endpoint and bus unvote when
disable endpoint. However, icc_path is released during endpoint disable
(by ep_pcie_clk_deinit()). This change fixes icc bus vote and adds icc bus
unvote accordingly.

Change-Id: Iaa4c6e4df5923a325f038dba689ef17bc746bab4
Signed-off-by: Can Guo <cang@codeaurora.org>