If the module does not have any modulemode, the _disable_module function
will do nothing. There is then no point waiting for a idle status change.

It will remove the following warnings.

[    0.331848] omap_hwmod: dmm: _wait_target_disable failed
[    0.339935] omap_hwmod: emif_fw: _wait_target_disable failed
[    0.348358] omap_hwmod: l3_main_1: _wait_target_disable failed
[    0.356964] omap_hwmod: l3_main_2: _wait_target_disable failed
[    0.365600] omap_hwmod: l4_abe: _wait_target_disable failed
[    0.373931] omap_hwmod: l4_cfg: _wait_target_disable failed
[    0.382263] omap_hwmod: l4_per: _wait_target_disable failed
[    0.391113] omap_hwmod: l4_wkup: _wait_target_disable failed
[    0.399536] omap_hwmod: dma_system: _wait_target_disable failed
[    0.408325] omap_hwmod: dss_core: _wait_target_disable failed
[    0.416839] omap_hwmod: dss_dispc: _wait_target_disable failed
[    0.425445] omap_hwmod: dss_dsi1: _wait_target_disable failed
[    0.433990] omap_hwmod: dss_dsi2: _wait_target_disable failed
[    0.442504] omap_hwmod: dss_hdmi: _wait_target_disable failed
[    0.451019] omap_hwmod: dss_rfbi: _wait_target_disable failed
[    0.459564] omap_hwmod: dss_venc: _wait_target_disable failed
[    0.489471] omap_hwmod: mailbox: _wait_target_disable failed
[    0.505920] omap_hwmod: spinlock: _wait_target_disable failed

Note: For such module, the state is managed automatically by HW according
to clock domain transition. It is then not possible to wait for idle even
later in the _idle function since the status will change at clock domain
boundary.
Signed-off-by: Benoit Cousson <b-cousson@ti.com>
Cc: Paul Walmsley <paul@pwsan.com>
Cc: Rajendra Nayak <rnayak@ti.com>
[paul@pwsan.com: renamed fns to indicate that they are OMAP4-only; moved
 _wait_target_disable() into _disable_module(), removing duplicate code]
Signed-off-by: Paul Walmsley <paul@pwsan.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>