memory: omap-gpmc: Fix compile test on SPARC

SPARC comes without CONFIG_OF_ADDRESS thus compile testing fails on
linking:

  /usr/bin/sparc64-linux-gnu-ld: drivers/memory/omap-gpmc.o: in function `gpmc_probe_generic_child':
  omap-gpmc.c:(.text.unlikely+0x14ec): undefined reference to `of_platform_device_create'

Fixes: ea0c0ad6 ("memory: Enable compile testing for most of the drivers")
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Acked-by: Roger Quadros <rogerq@ti.com>
Link: https://lore.kernel.org/r/20200911143251.399-1-krzk@kernel.org