src: use namespace prefix osmo_* for utils

src: use namespace prefix osmo_* for utils

Summary of changes:

s/bcd2char/osmo_bcd2char/g
s/char2bcd/osmo_char2bcd/g
s/hexparse/osmo_hexparse/g
s/hexdump/osmo_hexdump/g
s/hexdump_nospc/osmo_hexdump_nospc/g
s/ubit_dump/osmo_ubit_dump/g
s/static_assert/osmo_static_assert/g