Until the OMAP4 code is converted to disable the use of the clock
framework-based clockdomain enable/disable sequence, any clock used as
a hwmod main_clk must have a clockdomain associated with it.  This
patch populates some clock structure clockdomain names to resolve the
following warnings during kernel init:

omap_hwmod: dpll_mpu_m2_ck: missing clockdomain for dpll_mpu_m2_ck.
omap_hwmod: trace_clk_div_ck: missing clockdomain for trace_clk_div_ck.
omap_hwmod: l3_div_ck: missing clockdomain for l3_div_ck.
omap_hwmod: ddrphy_ck: missing clockdomain for ddrphy_ck.
Signed-off-by: Paul Walmsley <paul@pwsan.com>
Cc: Rajendra Nayak <rnayak@ti.com>
Cc: Benoît Cousson <b-cousson@ti.com>