ldso: fix unused variable warning

ldso: fix unused variable warning

This fixes the following warning when SUPPORT_LD_DEBUG_EARLY is not enabled:

ldso/ldso/ldso.c: In function '_dl_get_ready_to_run':
ldso/ldso/ldso.c:754:16: warning: unused variable 'tmp' [-Wunused-variable]

This was introduced with commit 94cc6edb (ldso: Rework global scope handling
and symbol lookup mechanism).

Cc: Filippo Arcidiacono <filippo.arcidiacono@st.com>
Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Bernhard Reutner-Fischer <rep.dot.nop@gmail.com>