ARM: OMAP4: Update timer clock aliases

Commit "ARM: dts: OMAP4: Update timer addresses" updated the device-tree
names of the OMAP4 timers 5-7 because the default address for the timers
was changed from the L3 address to the MPU private address. When booting
with device-tree, this introduces a regression when attempting to set
the parent clock of timers 5-7 to the sys_clk_div_ck. Therefore, update
the clock aliases for timer 5-7 to reflect the updated device-tree name
for the timers.

Signed-off-by: Jon Hunter <jon-hunter@ti.com>
[paul@pwsan.com: updated to apply after the CCF conversion]
Signed-off-by: Paul Walmsley <paul@pwsan.com>