ARM: 6790/1: SPEAr: Clock Framework: Rename usbd clock and align apb_clk entry

Reviewed-by: Stanley Miao <stanley.miao@windriver.com>
Signed-off-by: Deepak Sikri <deepak.sikri@st.com>
Signed-off-by: shiraz hashim <shiraz.hashim@st.com>
Signed-off-by: Viresh Kumar <viresh.kumar@st.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>