MIPS: remove .MIPS.abiflags section

The abiflags data is only used to communicate ABI information to a
program loader -- you can see what info is stored with readelf -A.
Dropping it shaves 24 bytes off of every binary (including plugins).

Change-Id: Iae78eeffe5c840ff67717707fb94821d24aac8ec

firmware/target/mips/ingenic_jz47xx/app.lds

@@ -111,6 +111,7 @@ SECTIONS
 
     /DISCARD/ :
     {
+        *(.MIPS.abiflags);
         *(.eh_frame);
         *(.rel.dyn);
     }