ARM: 9326/1: make <linux/uaccess.h> self-contained for ARM

When I compiled the following code for ARM, I encountered numerous
errors.

[Test Code]

    #include <linux/compiler.h>
    #include <linux/uaccess.h>

    int foo(int *x, int __user *ptr)
    {
            return get_user(*x, ptr);
    }

To fix the errors, make some asm headers self-contained:

 1. In arch/arm/include/asm/domain.h, include <linux/thread_info.h>
    for current_thread_info().

 2. In arch/arm/include/asm/traps.h, remove unneeded  __init, and
    include <linux/linkage.h> for asmlinkage.

 3. In arch/arm/include/asm/uaccess.h, include <linux/kernel.h> for
    might_fault().

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>