commonlib/cbfs: Make cbfsf_file_type public

Make cbfsf_file_type public to support detecting the payload type at
runtime. To be used by the following commits.

Possible payload types are:
* simple ELF
* FIT

Change-Id: I37e9fb06f926dc71b001722a6c3b6205a2f20462
Signed-off-by: Patrick Rudolph <patrick.rudolph@9elements.com>
Reviewed-on: https://review.coreboot.org/25859
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>
Reviewed-by: Julius Werner <jwerner@chromium.org>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/commonlib/cbfs.c

@@ -156,7 +156,7 @@ int cbfsf_decompression_info(struct cbfsf *fh, uint32_t *algo, size_t *size)
 	return 0;
 }
 
-static int cbfsf_file_type(struct cbfsf *fh, uint32_t *ftype)
+int cbfsf_file_type(struct cbfsf *fh, uint32_t *ftype)
 {
 	const size_t sz = sizeof(*ftype);