bl32: add an assert on BL32_SIZE in sp_min.ld.S

This assert is present in all other linker scripts. This checks the
size of BL32 doesn't exceed its defined limit.

Change-Id: I0005959b5591d3eebd870045adafe437108bc9e1
Signed-off-by: Yann Gautier <yann.gautier@st.com>

bl32/sp_min/sp_min.ld.S

@@ -140,4 +140,6 @@ SECTIONS
     __RW_END__ = .;
 
     __BL32_END__ = .;
+
+    ASSERT(. <= BL32_LIMIT, "BL32 image has exceeded its limit.")
 }