Rename local variables "m" and "regs" to less conflicting names

Rename local variables "m" and "regs" to less conflicting names

Rename "m" local macro variable to "__marker_counter_ptr".
Rename "regs" local macro variable to "__marker_regs".

Initial report:

The following trivial piece of code will result in corrupt events:

void dump_ackerman_current( int m, int n )
{
    trace_mark( ackerman, current, "m %d n %d", m, n );
}

This is because in ust/marker.h line 173 the definition of the
__trace_mark_counter macro uses a temporary named m (which shadows the
original m). It might be a good idea to use underscore variable names
inside these macros to make naming conflicts less likely.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Reported-by: Paul Wögerer <paul_woegerer@mentor.com>