Disable efi_debug in --enable-debug builds

Disable the additional EFI debugging in all builds.  Some users
run debug builds in production and the extra log messages can
cause confusion.  Beyond that the log messages are rarely useful.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Tony Hutter <hutter2@llnl.gov>
Closes #4523

lib/libefi/rdwr_efi.c

@@ -171,11 +171,7 @@ struct dk_map2  default_vtoc_map[NDKMAP] = {
 #endif			/* defined(_SUNOS_VTOC_16) */
 };
 
-#ifdef DEBUG
-int efi_debug = 1;
-#else
 int efi_debug = 0;
-#endif
 
 static int efi_read(int, struct dk_gpt *);