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>