ARM: at91: clock: fix the GCK's clock source

Before enabling a generated clock whose source is from the UPLL
clock, check and enable the UPLL clock.

Signed-off-by: Wenyou Yang <wenyou.yang@atmel.com>
Reviewed-by: Andreas Bießmann <andreas@biessmann.org>

arch/arm/mach-at91/armv7/clock.c

@@ -162,6 +162,11 @@ int at91_enable_periph_generated_clk(u32 id, u32 clk_source, u32 div)
 	if (div > 0xff)
 		return -EINVAL;
 
+	if (clk_source == GCK_CSS_UPLL_CLK) {
+		if (at91_upll_clk_enable())
+			return -ENODEV;
+	}
+
 	writel(id, &pmc->pcr);
 	regval = readl(&pmc->pcr);
 	regval &= ~AT91_PMC_PCR_GCKCSS;