scripts/code_cov_parse_info: take gcc IPA optimizations into account

When -O2/-O3 is used with GCC, IPA will produce function variants
at the object code. So, for a function or macro foo(), it may
produce several actual functions at the object code, like:

	foo.isra.3
	foo.isra.4

For the purposes of code coverage, all of those are the same
function, so use a regex with "\w+", which will exclude the
.isra.<number>, considering all variants as the same function.

Reviewed-by: Kamil Konieczny <kamil.konieczny@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>