C-SKY: add elf header definition for elfutils

This patch adds some defines relate to machine flag and section information,
which is used by elfutils elflint check. A C-SKY typo is also fixed with
this patch.

	* elf/elf.h (EF_CSKY_ABIMASK, EF_CSKY_OTHER, EF_CSKY_PROCESSOR)
	(EF_CSKY_ABIV1, EF_CSKY_ABIV2, SHT_CSKY_ATTRIBUTES): New defines.