In preparation for arm64 supporting ftrace built on other compiler
options, let's have Makefiles remove the $(CC_FLAGS_FTRACE) flags,
whatever these maybe, rather than assuming '-pg'.

While at it, fix arm32 as well. There should be no functional change as
a result of this patch.
Reviewed-by: NMark Rutland <mark.rutland@arm.com>
Acked-by: NArd Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: NTorsten Duwe <duwe@suse.de>
Signed-off-by: NWill Deacon <will.deacon@arm.com>