gdb/testsuite: use proc parameters in gdb.arch/amd64-osabi.exp

This test has a little oversight: the test procedure doesn't actually
use its parameters, the commands and expected patterns are hard-coded,
so we always test with i386:x86-64, instead of with the three arches.
Fix that.

gdb/testsuite/ChangeLog:

	* gdb.arch/amd64-osabi.exp (test_osabi_none): Use the
	parameters.

Change-Id: Iee2c32963d09e502ae791d5df2b6c04a1f49a57a