davinci: aemif: signedness bug in davinci_aemif_setup_timing()

aemif_calc_rate() can return a negative error value, so all the
variables that get tested for this value need to be signed.

The maximum bit width of WSETUP(WSETUP_MAX) appears to be 30 bits
(0xf << 26). Using a signed instead of an unsigned integer
shouldn't make a difference here.
Signed-off-by: Nicolas Kaiser <nikai@nikai.net>
Acked-by: Sekhar Nori <nsekhar@ti.com>
Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>

arch/arm/mach-davinci/aemif.c

@@ -90,7 +90,7 @@ int davinci_aemif_setup_timing(struct davinci_aemif_timing *t,
 					void __iomem *base, unsigned cs)
 {
 	unsigned set, val;
-	unsigned ta, rhold, rstrobe, rsetup, whold, wstrobe, wsetup;
+	int ta, rhold, rstrobe, rsetup, whold, wstrobe, wsetup;
 	unsigned offset = A1CR_OFFSET + cs * 4;
 	struct clk *aemif_clk;
 	unsigned long clkrate;