clk: nxp: clk-lpc32xx: rename clk_gate_is_enabled()

We need to export clk_gate_is_enabled() from clk framework, then
to avoid compilation issue we have to rename clk_gate_is_enabled()
in NXP LPC32xx clock driver.
We changed all gate op with 'lpc32xx_' prefix:
lpc32xx_clk_gate_enable(),
lpc32xx_clk_gate_disable(),
lpc32xx_clk_gate_is_enabled().

Signed-off-by: Gabriel Fernandez <gabriel.fernandez@st.com>
Acked-by: Vladimir Zapolskiy <vz@mleia.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>