hv: fixes related to unused API and uninitialized variable

This patch does:
- remove the unused API declaration
- fix use of uninitialized variable in instr_emul.c

Tracked-On: #861
Signed-off-by: Shiqing Gao <shiqing.gao@intel.com>
Acked-by: Eddie Dong <eddie.dong@intel.com>

hypervisor/release/logmsg.c

@@ -8,6 +8,5 @@
 
 void init_logmsg(__unused uint32_t flags) {}
 void do_logmsg(__unused uint32_t severity, __unused const char *fmt, ...) {}
-void print_logmsg_buffer(__unused uint16_t pcpu_id) {}
 void printf(__unused const char *fmt, ...) {}
 void vprintf(__unused const char *fmt, __unused va_list args) {}