ftrace: handle generic arch calls

The recordmcount script requires that the actual arch is passed in.
This works well when ARCH=i386 or ARCH=x86_64 but does not handle the
case of ARCH=x86.

This patch adds a parameter to the function to pass in the number of
bits of the architecture. So that it can determine if x86 should be
run for x86_64 or i386 archs.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>