swtpm: Add another exit label to avoid gcc -fanalyzer false positive

swtpm: Add another exit label to avoid gcc -fanalyzer false positive

Move existing exit label before the return statement and add another
label that includes the free(filebuffer). This avoids a false positive
by 'gcc -fanalyzer' that seems to think that free(filebuffer)
would double-free filebuffer after filebuffer = realloc(tmp, ..)
failure.

Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>