Use adapter No.1 but not No.0

Signed-off-by: Kevin Liu <airk908@gmail.com>
Rename mpu.c => mpu_reg.h

Too many reg, I don't want them in source file.

Signed-off-by: Kevin Liu <airk908@gmail.com>
Complete base function, read 3 sensors' data

Signed-off-by: Kevin Liu <airk908@gmail.com>