[PATCH] bogus BUILD_BUG_ON() in bpa_iommu

BUILD_BUG_ON(1) is asking for trouble (and getting it) when used in that
manner - dead code elimination happens after we parse it and invalid
type is invalid type, dead code or not.

It might be version-dependent, but at least 4.0.1 refuses to accept
that.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

arch/ppc64/kernel/bpa_iommu.c

@@ -99,7 +99,11 @@ get_iost_entry(unsigned long iopt_base, unsigned long io_address, unsigned page_
 		break;
 
 	default: /* not a known compile time constant */
-		BUILD_BUG_ON(1);
+		{
+			/* BUILD_BUG_ON() is not usable here */
+			extern void __get_iost_entry_bad_page_size(void);
+			__get_iost_entry_bad_page_size();
+		}
 		break;
 	}