soc: qcom: secure_buffer: Fix types and accessors when working with __le64

When the kernel is compiled with the sparse static analysis tool
enabled, the following warnings are emitted:

 drivers/soc/qcom//trace_secure_buffer.h:53:1: warning: incorrect type in
 assignment (different base types)
 drivers/soc/qcom//trace_secure_buffer.h:53:1: warning: incorrect type in
 assignment (different base types)
 drivers/soc/qcom//trace_secure_buffer.h:53:1: warning: invalid
 assignment: +=

Fix this by converting the type of the addrs variable from phys_addr_t
to u64, since the value we read into it is of type__le64 will always be
64 bits, while phys_addr_t may not be. Also, use the correct accessors
when accessing variables of type __le64.

Change-Id: Ia7e2394f2dc501dbf80f9035e0177555449dcfd8
Signed-off-by: Isaac J. Manjarres <isaacm@codeaurora.org>