clk: sunxi: fix overflow when setting up divided factors

Currently, we are allocating space for two pointers, when we actually
may need to store three of them (two divisors plus the original clock).
Fix this, and change sizeof(type) to sizeof(*var) to keep checkpatch.pl
happy.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Emilio López <emilio@elopez.com.ar>
Signed-off-by: Mike Turquette <mturquette@linaro.org>