qseecom: fix incomplete error handling for several functions

Perform a complete or adequate check of return codes for several
functions, including __qseecom_enable_clk, ion_do_cache_op and
ion_sg_table(), used by qseecom.

Change-Id: Ib1682bdc6d3034a22586af62a3d8986c54d369d5
Signed-off-by: Zhen Kong <zkong@codeaurora.org>