eeprom handling: Unify handling of boolean bit flags

eeprom handling: Unify handling of boolean bit flags

Boolean bit flags should be zero or one in memory,
not the actual eeprom value FTDI assigned to them.

Example of the code change in ftdi_eeprom_build():

ftdi_eeprom_build():
-            if (eeprom->suspend_dbus7 == SUSPEND_DBUS7_BIT)
+            if (eeprom->suspend_dbus7)

The changes should not break any backward compatibility
in ftdi_build_eeprom().

The function ftdi_decode_eeprom() will return slightly different values
for boolean fields, but callers should test using "if (flag_enabled)"
instead of "if (flag_enabled == specific_value)" anyway.

Test done: Decoded eeprom of a FT232 serial cable stayed the same.
$ diff -u dump-old.txt dump-new.txt
-> no change