clk: ti: am3-dpll: use custom API for memory access

Using the custom TI functions required not only replacing common memory
access functions but also rewriting the routines used to set bypass and
lock states. As for readl() and writel(), they also required the address
of the register to be accessed, a parameter that is hidden by the TI clk
module.

Signed-off-by: Dario Binacchi <dariobin@libero.it>