usb: musb: fix enumeration after resume

BugLink: https://bugs.launchpad.net/bugs/1775771

[ Upstream commit 17539f2f ]

On dm3730 there are enumeration problems after resume.
Investigation led to the cause that the MUSB_POWER_SOFTCONN
bit is not set. If it was set before suspend (because it
was enabled via musb_pullup()), it is set in
musb_restore_context() so the pullup is enabled. But then
musb_start() is called which overwrites MUSB_POWER and
therefore disables MUSB_POWER_SOFTCONN, so no pullup is
enabled and the device is not enumerated.

So let's do a subset of what musb_start() does
in the same way as musb_suspend() does it. Platform-specific
stuff it still called as there might be some phy-related stuff
which needs to be enabled.
Also interrupts are enabled, as it was the original idea
of calling musb_start() in musb_resume() according to
Commit 6fc6f4b8 ("usb: musb: Disable interrupts on suspend,
enable them on resume")
Signed-off-by: Andreas Kemnade <andreas@kemnade.info>
Tested-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Bin Liu <b-liu@ti.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Juerg Haefliger <juergh@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

drivers/usb/musb/musb_core.c

@@ -2522,7 +2522,8 @@ static int musb_resume(struct device *dev)
 	pm_runtime_set_active(dev);
 	pm_runtime_enable(dev);
 
-	musb_start(musb);
+	musb_enable_interrupts(musb);
+	musb_platform_enable(musb);
 
 	return 0;
 }