libhwc2.1: Properly check for preferred display config being set

* property_get() returns the value length, not a return code

04-20 21:27:48.222  6092  6137 D display : getPreferredDisplayConfigInternal: unable to find boot config for mode:
04-20 21:27:48.222  6114  6143 E HwcComposer: getPreferredBootDisplayConfig failed Status(-8, EX_SERVICE_SPECIFIC): '1: '
04-20 21:27:48.222  6114  6143 E HWComposer: getPreferredBootDisplayMode failed for display 4633128672291735808: BadConfig

Change-Id: I861a84b0a5c4b6f8bd58c322c614e07052e6c4b4
1 file changed
tree: 4ef0f557f3dd711ac1a17b6180bdf208f43a45c3
  1. base/
  2. exynos850/
  3. exynos9610/
  4. exynos9630/
  5. exynos9820/
  6. exynos990/
  7. Android.mk