ARM: pxa: ulpi: fix ulpi timeout and slowpath warn

ARM: pxa: ulpi: fix ulpi timeout and slowpath warn

Both cm-x300 and pxa3xx-ulpi use the plain clk_{en,dis}able() API.
With the new clocking framework this results in warnings of type:
------------[ cut here ]------------
WARNING: CPU: 0 PID: 1 at drivers/clk/clk.c:714 clk_core_enable+0x90/0x9c
Modules linked in:
CPU: 0 PID: 1 Comm: swapper Not tainted 4.15.0-rc5-cm-x300+ #15
Hardware name: CM-X300 module
[<c001007c>] (unwind_backtrace) from [<c000df94>] (show_stack+0x10/0x14)
[<c000df94>] (show_stack) from [<c00199a8>] (__warn+0xd8/0x100)
[<c00199a8>] (__warn) from [<c0019a0c>] (warn_slowpath_null+0x3c/0x48)
[<c0019a0c>] (warn_slowpath_null) from [<c024e8c0>] (clk_core_enable+0x90/0x9c)
[<c024e8c0>] (clk_core_enable) from [<c024ea54>] (clk_core_enable_lock+0x18/0x2c)
[<c024ea54>] (clk_core_enable_lock) from [<c0016994>] (cm_x300_u2d_init+0x4c/0xe8)
[<c0016994>] (cm_x300_u2d_init) from [<c00163e0>] (pxa3xx_u2d_probe+0xe0/0x244)
[<c00163e0>] (pxa3xx_u2d_probe) from [<c0283de0>] (platform_drv_probe+0x38/0x88)
...
------------[ cut here ]------------
and alike...

And finally, it results in:
------------[ cut here ]------------
pxa310_ulpi_poll: ULPI access timed out!
OTG transceiver init failed
------------[ cut here ]------------

It might be that disabling the warning in kernel config would also do
the job, but IMO a better solution would be to switch to
clk_prepare_enable() and clk_disable_unprepare() APIs.

Signed-off-by: Igor Grinberg <grinberg@compulab.co.il>
Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>