i2c: thunderx: Adding ioclk support

Read the ioclk property as reference clock if sclk not present in acpi
table to make it SOC agnostic.
In case, it's not populated from dts/acpi table, use the default clock
of 800 MHz which is optimal in either case of sclk/ioclk.
Signed-off-by: Piyush Malgujar <pmalgujar@marvell.com>
Acked-by: Andi Shyti <andi.shyti@kernel.org>
Signed-off-by: Andi Shyti <andi.shyti@kernel.org>

drivers/i2c/busses/i2c-thunderx-pcidrv.c

@@ -27,7 +27,7 @@
 
 #define PCI_DEVICE_ID_THUNDER_TWSI	0xa012
 
-#define SYS_FREQ_DEFAULT		700000000
+#define SYS_FREQ_DEFAULT		800000000
 #define OTX2_REF_FREQ_DEFAULT		100000000
 
 #define TWSI_INT_ENA_W1C		0x1028
@@ -100,7 +100,8 @@ static void thunder_i2c_clock_enable(struct device *dev, struct octeon_i2c *i2c)
 		i2c->sys_freq = clk_get_rate(i2c->clk);
 	} else {
 		/* ACPI */
-		device_property_read_u32(dev, "sclk", &i2c->sys_freq);
+		if (device_property_read_u32(dev, "sclk", &i2c->sys_freq))
+			device_property_read_u32(dev, "ioclk", &i2c->sys_freq);
 	}
 
 skip: