Fix spelling errors

seperate -> separate

bfd/ChangeLog:

2020-01-17  Christian Biesinger  <cbiesinger@google.com>

	* coff-arm.c: Fix spelling error (seperate).
	* elfxx-riscv.c (riscv_parse_sv_or_non_std_ext): Fix spelling
	error (seperate).
	* sysdep.h (strnlen): Fix spelling error (seperate).

opcodes/ChangeLog:

2020-01-17  Christian Biesinger  <cbiesinger@google.com>

	* opintl.h: Fix spelling error (seperate).

sim/arm/ChangeLog:

2020-01-17  Christian Biesinger  <cbiesinger@google.com>

	* iwmmxt.c: Fix spelling error (seperate).

Change-Id: I55e5f47bcf3cf3533d2acb7ad338f1be0d5f30f9