arm, davinci: Rename AM1808 lowlevel functions to DA850

arm, davinci: Rename AM1808 lowlevel functions to DA850

Rename arch/arm/cpu/arm926ejs/davinci/am1808_lowlevel.c and
arch/arm/include/asm/arch-davinci/am1808_lowlevel.h to da850_lowlevel.c
and da850_lowlevel.h since they apply not only to the AM1808 SoC
but to all DA850 chips. The function names and #defines are changed
likewise.

Signed-off-by: Christian Riesch <[email protected]>
Cc: Heiko Schocher <[email protected]>
Cc: Paulraj Sandeep <[email protected]>
Cc: Albert ARIBAUD <[email protected]>
Acked-by: Heiko Schocher <[email protected]>
Signed-off-by: Sandeep Paulraj <[email protected]>