log: improve blob printout format
log: improve blob printout format

For big blobs don't allocate the whole buffer on the stack
at once, but process one line at a time, with a fixed length
buffer.
Make the output more hexdump like, with indexes and ascii
output, which is quite helpful when debugging data containing
strings, like PEM certs, etc. Example BLOG_DEBUG output
for an EK cert before:

debug:fapi:ifapi_get_intl_ek_certificate() Certificate (size=1665):
	7b22707562686173
	68223a222d356569
	555f566c64582d58
	38544d6252305045
.....
and after:

debug:fapi:ifapi_get_intl_ek_certificate() Certificate (size=1665):
0000: 7b2270756268617368223a222d356569  {"pubhash":"-5ei
0010: 555f566c64582d5838544d6252305045  U_VldX-X8TMbR0PE
0020: 433943576c594a357075316345623959  C9CWlYJ5pu1cEb9Y
0030: 454d4a5445424d253344222c22636572  EMJTEBM%3D","cer
0040: 7469666963617465223a224d4949456e  tificate":"MIIEn
....
Signed-off-by: Tadeusz Struk <ac7da5bc34fbda078ba4af5ef710d2a59a2316f5@intel.com>

01org/TPM2.0-TSS,tpm2-software/tpm2-tss,01org/TPM2.0-TSS,01org/TPM2.0-TSS,01org/tpm2-tss,01org/tpm2-tss,tpm2-software/tpm2-tss,01org/tpm2-tss,tpm2-software/tpm2-tss,01org/TPM2.0-TSS