WHENCE: Remove references to source for emi62 firmware

The 'sources' appear to be the names of ihex files, not actual source
code, and in any case those files are not included in this repository.
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

WHENCE

@@ -221,17 +221,14 @@ Version: 1.0.0.191
 Info: DATE= 2002oct28
 
 File: emi62/loader.fw
-Source: EMILOAD.HEX
 Version: 1.0.2.002
 Info: DATE=10.01.2002
 
 File: emi62/midi.fw
-Source: EMI62MFW.HEX
 Version: 1.04.062
 Info: DATE=16.10.2002
 
 File: emi62/spdif.fw
-Source: EMI62SFW.HEX
 Version: 1.04.062
 Info: DATE=16.10.2002