lpc32xx: remove duplicated DMA_CLK_ENABLE bit definition

lpc32xx: remove duplicated DMA_CLK_ENABLE bit definition

Because there is an originally defined CLK_DMA_ENABLE macro in clk.h,
no reason to add another DMA_CLK_ENABLE macro with the same value.

Remove DMA_CLK_ENABLE, since it does not follow naming convention from
the code, this implies renaming of DMA_CLK_ENABLE to CLK_DMA_ENABLE in
lpc32xx/devices.c file.

Signed-off-by: Vladimir Zapolskiy <vz@mleia.com>
Tested-by: Sylvain Lemieux <slemieux@tycoint.com>