arch/tile: various header improvements for building drivers

This change adds a number of missing headers in asm (fb.h, parport.h,
serial.h, and vga.h) using the minimal generic versions.

It also adds a number of missing interfaces that showed up as build
failures when trying to build various drivers not normally included in the
"tile" distribution: ioremap_wc(), memset_io(), io{read,write}{16,32}be(),
virt_to_bus(), bus_to_virt(), irq_canonicalize(), __pte(), __pgd(),
and __pmd().  I also added a cast in virt_to_page() since not all callers
pass a pointer.

I fixed <asm/stat.h> to properly include a __KERNEL__ guard for the
__ARCH_WANT_STAT64 symbol, and <asm/swab.h> to use __builtin_bswap32()
even for our 64-bit architecture, since the same code is produced.

I added an export for get_cycles(), since it's used in some modules.

And I made <arch/spr_def.h> properly include the __KERNEL__ guard,
even though it's not yet exported, since it likely will be soon.

Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>

arch/tile/kernel/time.c

@@ -22,6 +22,7 @@
 #include <linux/sched.h>
 #include <linux/smp.h>
 #include <linux/delay.h>
+#include <linux/module.h>
 #include <asm/irq_regs.h>
 #include <asm/traps.h>
 #include <hv/hypervisor.h>
@@ -56,6 +57,7 @@ cycles_t get_cycles(void)
 
 	return (((cycles_t)high) << 32) | low;
 }
+EXPORT_SYMBOL(get_cycles);
 #endif
 
 /*