ARM: OMAP2+: Fix ti_sysc_find_one_clockdomain to check for to_clk_hw_omap

We must bail out early if the clock is not hw_omap. Otherwise we will
try to access invalid address with hwclk->clkdm_name:

Unable to handle kernel paging request at virtual address ffffffff
Internal error: Oops: 27 [#1] ARM
...
(strcmp) from [<c011b348>] (clkdm_lookup+0x40/0x60)
[<c011b348>] (clkdm_lookup) from [<c011cb84>] (ti_sysc_clkdm_init+0x5c/0x64)
[<c011cb84>] (ti_sysc_clkdm_init) from [<c03680a8>] (sysc_probe+0x948/0x117c)
[<c03680a8>] (sysc_probe) from [<c03d0af4>] (platform_drv_probe+0x48/0x98)
...

Fixes: 2b2f7def ("bus: ti-sysc: Add support for missing clockdomain handling")
Signed-off-by: Tony Lindgren <tony@atomide.com>