[asan] Remove FreeBSD XFAIL from asan-sigbus.cpp test

This test passes for me on FreeBSD 12.2 and was probably fixed by
https://svnweb.freebsd.org/base?view=revision&revision=352807.

Reviewed By: emaste

Differential Revision: https://reviews.llvm.org/D98281

compiler-rt/test/asan/TestCases/Posix/asan-sigbus.cpp

@@ -5,8 +5,6 @@
 // RUN: %env_asan_opts=handle_sigbus=0 not --crash %run %t 2>&1 | FileCheck %s
 
 // UNSUPPORTED: ios
-// Instead of getting a SIGBUS error, we get a SIGSEGV
-// XFAIL: freebsd
 
 #include <assert.h>
 #include <fcntl.h>