tools/mgmt-tester: Fix expected HCI command accounting

tools/mgmt-tester: Fix expected HCI command accounting

This fixes test condition count in the expected HCI command
callback.

When the expected HCI opcode is detected, mark the condition
as done. Any subsequent HCI commands are ignored.

Without this fix, in couple of test cases where the expected HCI
command is detected more than once, the test may be erroneously
reported as a failure or prematurely declared as a success before
waiting on an expected MGMT event condition.

The test cases where this behavior is fixed:
Remove Ext Advertising - Success 1
Remove Ext Advertising - Success 2
Reviewed-by: Tedd Ho-Jeong An <tedd.an@intel.com>
Signed-off-by: Anuj Jain <anuj01.jain@samsung.com>
Signed-off-by: Ayush Garg <ayush.garg@samsung.com>