x86/fpu: Get rid of fpu__get_supported_xfeatures_mask()

This function is really not doing what the comment advertises:

 "Find supported xfeatures based on cpu features and command-line input.
  This must be called after fpu__init_parse_early_param() is called and
  xfeatures_mask is enumerated."

fpu__init_parse_early_param() does not exist anymore and the function just
returns a constant.

Remove it and fix the caller and get rid of further references to
fpu__init_parse_early_param().

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210623121451.816404717@linutronix.de