CHROMIUM: Remove "DP Hotplug" in mach-exynos.

CHROMIUM: Remove "DP Hotplug" in mach-exynos.

Spring is not using the dedicated DP_HPD pin (but a vanilla GPIO)

The only difference between calling exynos_fimd_gpio_setup_24bpp() and calling
exynos_fimd_gpio_setup_24bpp() (which is actually called by the former) is the
pin muxing for DP_HPD pin (aka GPX0_7)

BUG=chrome-os-partner:16196
TEST=See that slimport driver gets through initialization.

Change-Id: I5d26228d4a3027f9669022dc3a12ead70cf202b4
Signed-off-by: Jeremy Thorpe <jeremyt@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/50538