i2c: aspeed: Add an explicit type casting for *get_clk_reg_val

This commit fixes this sparse warning:
drivers/i2c/busses/i2c-aspeed.c:875:38: warning: incorrect type in assignment (different modifiers)
drivers/i2c/busses/i2c-aspeed.c:875:38:    expected unsigned int ( *get_clk_reg_val )( ... )
drivers/i2c/busses/i2c-aspeed.c:875:38:    got void const *const data

Reported-by: Wolfram Sang <wsa@the-dreams.de>
Signed-off-by: Jae Hyun Yoo <jae.hyun.yoo@linux.intel.com>
Reviewed-by: Brendan Higgins <brendanhiggins@google.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

drivers/i2c/busses/i2c-aspeed.c

@@ -872,7 +872,7 @@ static int aspeed_i2c_probe_bus(struct platform_device *pdev)
 	if (!match)
 		bus->get_clk_reg_val = aspeed_i2c_24xx_get_clk_reg_val;
 	else
-		bus->get_clk_reg_val = match->data;
+		bus->get_clk_reg_val = (u32 (*)(u32))match->data;
 
 	/* Initialize the I2C adapter */
 	spin_lock_init(&bus->lock);