ldso/mips: Clean up warnings

Trivial fixes for these warnings:

  CC ldso/libdl/libdl.oS
In file included from ldso/ldso/ldso.c:46:0:
ldso/ldso/mips/elfinterp.c:88:1: warning: no previous prototype for '__dl_runtime_pltresolve'
ldso/ldso/ldso.c: In function '_dl_get_ready_to_run':
ldso/ldso/ldso.c:475:5: warning: assignment makes pointer from integer without a cast
In file included from ldso/ldso/ldso.c:1097:0:
ldso/ldso/dl-elf.c: In function '_dl_load_elf_shared_library':
ldso/ldso/dl-elf.c:811:3: warning: assignment makes pointer from integer without a cast

Signed-off-by: Kevin Cernekee <cernekee@gmail.com>
Signed-off-by: Carmelo Amoroso <carmelo.amoroso@st.com>

ldso/ldso/mips/dl-sysdep.h

@@ -130,7 +130,7 @@ do {										\
 	GOT_BASE[0] = (unsigned long) _dl_runtime_resolve;			\
 	GOT_BASE[1] = (unsigned long) MODULE;					\
 										\
-	pltgot = MODULE->dynamic_info[DT_MIPS_PLTGOT_IDX];			\
+	pltgot = (unsigned long *) MODULE->dynamic_info[DT_MIPS_PLTGOT_IDX];	\
 	if (pltgot) {								\
 		pltgot[0] = (unsigned long) _dl_runtime_pltresolve;		\
 		pltgot[1] = (unsigned long) MODULE;				\
@@ -159,6 +159,9 @@ unsigned long __dl_runtime_resolve(unsigned long sym_index,
 	unsigned long old_gpreg);
 
 struct elf_resolve;
+unsigned long __dl_runtime_pltresolve(struct elf_resolve *tpnt,
+	int reloc_entry);
+
 void _dl_perform_mips_global_got_relocations(struct elf_resolve *tpnt, int lazy);
 
 /* 4096 bytes alignment */