symbol: replace find_symbol() by get_dso_symbols()

Old find_symbol() just find symbol by name, the new one
get_dso_symbols() will return all symbols/notes.

And user of this functions, will match name/pattern by itself.

For now get_dso_symbols() used like find_symbol(), this behaviour will
be changed in next patches.

Signed-off-by: Azat Khuzhin <a3at.mail@gmail.com>