ltq-deu: remove compiler warning and shorten locked sections

Removing hash pointer in _hmac_setkey since its not needed and causes
a compiler warning.
Make the spinlock control sections shorter and move initializations
out of the control sections to free the spinlock faster for allowing
other threads to use the hash engine.
Minor improvements for indentation and removal of blanks and blank
lines in some areas.

Signed-off-by: Daniel Kestrel <kestrel1974@t-online.de>