This is a quality of life helper for plugins so they don't need to
re-implement symbol lookup when dumping an address. The strings are
constant so don't need to be duplicated. One minor tweak is to return
NULL instead of a zero length string to show lookup failed.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Mahmoud Mandour <ma.mandourr@gmail.com>
Message-Id: <20210608040532.56449-2-ma.mandourr@gmail.com>
Message-Id: <20210623102749.25686-8-alex.bennee@linaro.org>