kallsyms: support kernel symbols in Blackfin on-chip memory

The Blackfin arch has a discontiguous .text layout due to having on-chip
instruction memory and no virtual memory support.  As such, we need to
add explicit checks for these additional .text regions.

Signed-off-by: Robin Getz <robin.getz@analog.com>
Signed-off-by: Bryan Wu <cooloney@kernel.org>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>