gas: dw2gencfi: use all_cfi_sections instead of cfi_sections

The code in dw2gencfi.c was checking variable cfi_sections and
all_cfi_sections seemingly randomly.  Accessing all_cfi_sections seems
to the correct variable to access.

The data in cfi_sections has already been propagated to all_cfi_sections
once cfi_dot_startproc () has been called.

gas/
        * dw2gencfi.c (dot_cfi_startproc): Use all_cfi_sections
	instead.
        (dot_cfi_endproc): Likewise.
        (dot_cfi_fde_data): Likewise.