Fix mistake in Makefile that prevented build of
of_init.o

With this fix smc shows up in iomem like this:

  0xffffe400 - 0xffffe5ff (size 0x00000200) at91sam9-smc0
  0xffffea00 - 0xffffebff (size 0x00000200) at91sam9-smc1

And we get access to the files from defaultenv provided by the board

Fixes: b467c262b5a7 (at91sam9263ek: enable DT support)
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>