util/cbfstool: Print max empty entry size in error message

Currently, cbfstool prints the following error message when the added
file doesn't fit in the region:

 E: Could not add [file, 1024 bytes (1 KB)@0x0]; too big?

It requires manual inspection to know the space left in the region. To
make that easier, also print the maximum empty CBFS entry size in the
error message:

 E: Could not add file [header 76 + content 1024 bytes (1 KB)] @0x0;
 Largest empty slot: 512 bytes

Change-Id: I00bcc83abe8b0a33dcd7b75521e6cfccd8953661
Signed-off-by: Yu-Ping Wu <yupingso@chromium.org>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/84204
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Yidi Lin <yidilin@google.com>

0 files changed, 0 insertions, 0 deletions