declance: Remove `incompatible pointer type' warnings

Revert damage caused by 43d620c8:

.../declance.c: In function 'cp_to_buf':
.../declance.c:347: warning: assignment from incompatible pointer type
.../declance.c:348: warning: assignment from incompatible pointer type
.../declance.c: In function 'cp_from_buf':
.../declance.c:406: warning: assignment from incompatible pointer type
.../declance.c:407: warning: assignment from incompatible pointer type

Also add a `const' qualifier where applicable and adjust formatting.

Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org>
Signed-off-by: David S. Miller <davem@davemloft.net>