drm/bridge: it6505: update usleep_range for RC circuit charge time

The spec of timing between IVDD/OVDD and SYSRTEN is 10ms, but SYSRSTN RC
circuit need at least 25ms for rising time, update for match spec

Signed-off-by: Kuro Chung <kuro.chung@ite.com.tw>
Signed-off-by: Hermes Wu <hermes.wu@ite.com.tw>
Reviewed-by: Robert Foss <rfoss@kernel.org>
Signed-off-by: Robert Foss <rfoss@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20240604024405.1122488-1-kuro.chung@ite.com.tw