[Intel-gfx] [PATCH] drm/i915: Use usleep_range() in wait_for()

[shuang.he at intel.com]

Tested-By: PRC QA PRTS (Patch Regression Test System Contact: shuang.he at intel.com)
Task id: 6020
-------------------------------------Summary-------------------------------------
Platform          Delta          drm-intel-nightly          Series Applied
PNV                 -2              274/274              272/274
ILK                                  303/303              303/303
SNB                                  303/303              303/303
IVB                 -2              342/342              340/342
BYT                                  287/287              287/287
HSW                                  362/362              362/362
BDW                                  308/308              308/308
-------------------------------------Detailed-------------------------------------
Platform  Test                                drm-intel-nightly          Series Applied
 PNV  igt_gem_userptr_blits_minor-sync-interruptible      DMESG_WARN(1)PASS(3)      DMESG_WARN(1)PASS(1)
*PNV  igt_gen3_render_linear_blits      FAIL(1)PASS(6)      CRASH(1)PASS(1)
 IVB  igt_gem_pwrite_pread_snooped-copy-performance      DMESG_WARN(2)PASS(3)      DMESG_WARN(1)PASS(1)
*IVB  igt_gem_storedw_batches_loop_secure-dispatch      PASS(4)      DMESG_WARN(1)PASS(1)
Note: You need to pay more attention to line start with '*'