ARM: OMAP2+: clock/dpll: fix _dpll_test_fint arithmetics overflow

The divider value provided to the _dpll_test_fint can reach value of
256 with J type DPLLs (USB etc.), which causes an overflow with the u8
datatype. Fix this by changing the parameter to be an int instead.

Signed-off-by: Tero Kristo <t-kristo@ti.com>
[paul@pwsan.com: changed type of 'n' to unsigned int]
Signed-off-by: Paul Walmsley <paul@pwsan.com>