m32r: fix build warning

While building m32r defconfig we got warnings:

  arch/m32r/platforms/m32700ut/setup.c:249:24: warning: 'm32700ut_lcdpld_irq_type' defined but not used [-Wunused-variable]

m32700ut_lcdpld_irq_type is only used when CONFIG_USB is enabled.
Modify the code to declare the related variables and functions only when
CONFIG_USB is enabled.

Link: http://lkml.kernel.org/r/1479244406-7507-1-git-send-email-sudipm.mukherjee@gmail.com
Signed-off-by: Sudip Mukherjee <sudip.mukherjee@codethink.co.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/m32r/platforms/m32700ut/setup.c

@@ -201,6 +201,7 @@ static struct irq_chip m32700ut_lanpld_irq_type =
 #define lcdpldirq2port(x)	(unsigned long)((int)M32700UT_LCD_ICUCR1 + \
 				 (((x) - 1) * sizeof(unsigned short)))
 
+#ifdef CONFIG_USB
 static pld_icu_data_t lcdpld_icu_data[M32700UT_NUM_LCD_PLD_IRQ];
 
 static void disable_m32700ut_lcdpld_irq(unsigned int irq)
@@ -253,6 +254,7 @@ static struct irq_chip m32700ut_lcdpld_irq_type =
 	.irq_mask	= mask_m32700ut_lcdpld,
 	.irq_unmask	= unmask_m32700ut_lcdpld,
 };
+#endif
 
 void __init init_IRQ(void)
 {