x86: remove more uaccess_32.h complexity

I'm looking at trying to possibly merge the 32-bit and 64-bit versions
of the x86 uaccess.h implementation, but first this needs to be cleaned
up.

For example, the 32-bit version of "__copy_from_user_inatomic()" is
mostly the special cases for the constant size, and it's actually almost
never relevant.  Most users aren't actually using a constant size
anyway, and the few cases that do small constant copies are better off
just using __get_user() instead.

So get rid of the unnecessary complexity.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/maccess.c

@@ -96,8 +96,7 @@ long strncpy_from_unsafe(char *dst, const void *unsafe_addr, long count)
 	pagefault_disable();
 
 	do {
-		ret = __copy_from_user_inatomic(dst++,
-						(const void __user __force *)src++, 1);
+		ret = __get_user(*dst++, (const char __user __force *)src++);
 	} while (dst[-1] && ret == 0 && src - unsafe_addr < count);
 
 	dst[-1] = '\0';