ARM: OMAP2+: Check omap3-rom-rng for GP device instead of HS device

In general we should check for GP device instead of HS device unless
the other options such as EMU are also checked. Otherwise omap3-rom-rng
won't probe on few of the old n900 macro boards still in service in
automated build and boot test systems.

Cc: Aaro Koskinen <aaro.koskinen@iki.fi>
Cc: Adam Ford <aford173@gmail.com>
Cc: Pali Rohár <pali.rohar@gmail.com>
Cc: Sebastian Reichel <sre@kernel.org>
Cc: Tero Kristo <t-kristo@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>