irqchip: crossbar: Fix kerneldoc warning

Adding missing properties for kerneldoc (@write) and cleanup
of harmless warnings while we are here.

kerneldoc warnings:
Warning(drivers/irqchip/irq-crossbar.c:27): missing initial short description on line:
 * struct crossbar_device: crossbar device description
Info(drivers/irqchip/irq-crossbar.c:27): Scanning doc for struct
Warning(drivers/irqchip/irq-crossbar.c:39): No description found for parameter 'write'
2 warnings
Signed-off-by: Nishanth Menon <nm@ti.com>
Signed-off-by: Sricharan R <r.sricharan@ti.com>
Acked-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Link: https://lkml.kernel.org/r/1403766634-18543-9-git-send-email-r.sricharan@ti.comSigned-off-by: Jason Cooper <jason@lakedaemon.net>

drivers/irqchip/irq-crossbar.c

@@ -22,12 +22,14 @@
 #define IRQ_SKIP	-3
 #define GIC_IRQ_START	32
 
-/*
+/**
+ * struct crossbar_device - crossbar device description
  * @int_max: maximum number of supported interrupts
  * @safe_map: safe default value to initialize the crossbar
  * @irq_map: array of interrupts to crossbar number mapping
  * @crossbar_base: crossbar base address
  * @register_offsets: offsets for each irq number
+ * @write: register write function pointer
  */
 struct crossbar_device {
 	uint int_max;