MIPS: ath79: Allow using ath79_ddr_wb_flush() from drivers

Move the declaration of ath79_ddr_wb_flush() to asm/mach-ath79/ath79.h
to allow using it from drivers. This is needed to move the CPU IRQ
driver to drivers/irqchip.

Signed-off-by: Alban Bedel <[e-mail]>
Cc: Thomas Gleixner <[e-mail]>
Cc: Jason Cooper <[e-mail]>
Cc: Marc Zyngier <[e-mail]>
Cc: Alexander Couzens <[e-mail]>
Cc: Joel Porquet <[e-mail]>
Cc: Andrew Bresticker <[e-mail]>
Cc: [e-mail]
Cc: [e-mail]
Patchwork: https://patchwork.linux-mips.org/patch/11502/
Signed-off-by: Ralf Baechle <[e-mail]>

arch/mips/ath79/common.h

···
 unsigned long ath79_get_sys_clk_rate(const char *id);
 
 void ath79_ddr_ctrl_init(void);
-void ath79_ddr_wb_flush(unsigned int reg);
 
 void ath79_gpio_init(void);
 

arch/mips/include/asm/mach-ath79/ath79.h

···
 	return soc_is_qca9556() || soc_is_qca9558();
 }
 
+void ath79_ddr_wb_flush(unsigned int reg);
 void ath79_ddr_set_pci_windows(void);
 
 extern void __iomem *ath79_pll_base;