sh: pci: Support secondary FPGA-driven PCIe clocks on SDK7786.

The SDK7786 FPGA has secondary control over the PCIe clocks, specifically
relating to the slots and oscillator. This ties the FPGA clocks in to the
clock framework and balances the refcounting similar to how the primary
on-chip clocks are managed. While the on-chip clocks are per-port, the
FPGA clock enable/disable is global for the entire block.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>

arch/sh/include/mach-sdk7786/mach/fpga.h

@@ -39,7 +39,7 @@
 #define  PCIECR_PRST3		BIT(11) /* slot 3 card present */
 #define  PCIECR_PRST2		BIT(10) /* slot 2 card present */
 #define  PCIECR_PRST1		BIT(9)  /* slot 1 card present */
-#define  PCIECR_CLKEN		BIT(4)
+#define  PCIECR_CLKEN		BIT(4)	/* oscillator enable */
 
 #define FAER		0x150
 #define USRGPIR		0x160