[ARM] sparse: fix several warnings

arch/arm/kernel/process.c:270:6: warning: symbol 'show_fpregs' was not declared. Should it be static?

This function isn't used, so can be removed.

arch/arm/kernel/setup.c:532:9: warning: symbol 'len' shadows an earlier one
arch/arm/kernel/setup.c:524:6: originally declared here

A function containing two 'len's.

arch/arm/mm/fault-armv.c:188:13: warning: symbol 'check_writebuffer_bugs' was not declared. Should it be static?
arch/arm/mm/mmap.c:122:5: warning: symbol 'valid_phys_addr_range' was not declared. Should it be static?
arch/arm/mm/mmap.c:137:5: warning: symbol 'valid_mmap_phys_addr_range' was not declared. Should it be static?

Missing includes.

arch/arm/kernel/traps.c:71:77: warning: Using plain integer as NULL pointer
arch/arm/mm/ioremap.c:355:46: error: incompatible types in comparison expression (different address spaces)

Sillies.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
diff --git a/arch/arm/kernel/traps.c b/arch/arm/kernel/traps.c
index 46e2c83..13f8f18 100644
--- a/arch/arm/kernel/traps.c
+++ b/arch/arm/kernel/traps.c
@@ -68,7 +68,8 @@
  */
 static int verify_stack(unsigned long sp)
 {
-	if (sp < PAGE_OFFSET || (sp > (unsigned long)high_memory && high_memory != 0))
+	if (sp < PAGE_OFFSET ||
+	    (sp > (unsigned long)high_memory && high_memory != NULL))
 		return -EFAULT;
 
 	return 0;