i2c-omap: Don't compile in OMAP15xx I2C ISR for non-OMAP15xx builds

Skip compiling OMAP15xx I2C ISR for non-OMAP15xx builds.  Saves 400 bytes
of text for most OMAP builds.
Signed-off-by: NPaul Walmsley <paul@pwsan.com>
Signed-off-by: NTony Lindgren <tony@atomide.com>

drivers/i2c/busses/i2c-omap.c

@@ -503,6 +503,9 @@ omap_i2c_ack_stat(struct omap_i2c_dev *dev, u16 stat)
 	omap_i2c_write_reg(dev, OMAP_I2C_STAT_REG, stat);
 }
 
+/* rev1 devices are apparently only on some 15xx */
+#ifdef CONFIG_ARCH_OMAP15XX
+
 static irqreturn_t
 omap_i2c_rev1_isr(int this_irq, void *dev_id)
 {
@@ -557,6 +560,9 @@ omap_i2c_rev1_isr(int this_irq, void *dev_id)
 
 	return IRQ_HANDLED;
 }
+#else
+#define omap_i2c_rev1_isr		0
+#endif
 
 static irqreturn_t
 omap_i2c_isr(int this_irq, void *dev_id)