ARC: Use elf32-bigarc in case of -EB

As it is stated in LD manual [1] the second entry in OUTPUT_FORMAT
corresponds to "-EB" command-line option which for us is "elf32-bigarc".

[1] https://sourceware.org/binutils/docs/ld/Format-Commands.html#Format-Commands

Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>

arch/arc/cpu/u-boot.lds

@@ -5,7 +5,7 @@
 
 #include <config.h>
 
-OUTPUT_FORMAT("elf32-littlearc", "elf32-littlearc", "elf32-littlearc")
+OUTPUT_FORMAT("elf32-littlearc", "elf32-bigarc", "elf32-littlearc")
 OUTPUT_ARCH(arc)
 ENTRY(_start)
 SECTIONS