ARM: OMAP1: DMTIMER: fix broken timer clock source selection

ARM: OMAP1: DMTIMER: fix broken timer clock source selection

DMTIMER source selection on OMAP1 is broken.  omap1_dm_timer_set_src()
tries to use __raw_{read,write}l() to read from and write to physical
addresses, but those functions take virtual addresses.

sparse caught this:

arch/arm/mach-omap1/timer.c:50:13: warning: incorrect type in argument 1 (different base types)
arch/arm/mach-omap1/timer.c:50:13:    expected void const volatile [noderef] <asn:2>*<noident>
arch/arm/mach-omap1/timer.c:50:13:    got unsigned int
arch/arm/mach-omap1/timer.c:52:9: warning: incorrect type in argument 1 (different base types)
arch/arm/mach-omap1/timer.c:52:9:    expected void const volatile [noderef] <asn:2>*<noident>
arch/arm/mach-omap1/timer.c:52:9:    got unsigned int

Fix by using omap_{read,writel}(), just like the other users of the
MOD_CONF_CTRL_1 register in the OMAP1 codebase.  Of course, in the long term,
removing omap_{read,write}l() is the appropriate thing to do; but
this will take some work to do this cleanly.

Looks like this was caused by 97933d6 (ARM: OMAP1: dmtimer: conversion
to platform devices) that dangerously moved code and changed it in
the same patch.

Signed-off-by: Paul Walmsley <paul@pwsan.com>
Cc: Tarun Kanti DebBarma <tarun.kanti@ti.com>
Cc: stable@vger.kernel.org
[tony@atomide.com: updated comments to include the breaking commit]
Signed-off-by: Tony Lindgren <tony@atomide.com>