i.MX51: Use correct clock for gpt

The gpt uses the ipg clock, not ipg_perclk
Signed-off-by: NSascha Hauer <s.hauer@pengutronix.de>

arch/arm/mach-mx5/clock-mx51.c

@@ -757,7 +757,7 @@ DEFINE_CLOCK(uart3_ipg_clk, 2, MXC_CCM_CCGR1, MXC_CCM_CCGRx_CG7_OFFSET,
 
 /* GPT */
 DEFINE_CLOCK(gpt_clk, 0, MXC_CCM_CCGR2, MXC_CCM_CCGRx_CG9_OFFSET,
-	NULL,  NULL, &ipg_perclk, NULL);
+	NULL,  NULL, &ipg_clk, NULL);
 DEFINE_CLOCK(gpt_ipg_clk, 0, MXC_CCM_CCGR2, MXC_CCM_CCGRx_CG10_OFFSET,
 	NULL,  NULL, &ipg_clk, NULL);