iio: accel: fix Kconfig warning

commit 76222772
"iio: accel: st_accel: handle deprecated bindings"
attempted to be smart and let users use the old I2C
driver and the new SPI driver, or the old SPI driver and
the new I2C driver in combination for the LIS3LV02,
and put the restrictions on the I2C and SPI subdrivers
not not be combined with the old subdrivers.

This doesn't work since the IIO ST accel top-level
component selects the I2C and SPI subdrivers, resulting
in the following Kconfig noise:

warning: (IIO_ST_ACCEL_3AXIS) selects IIO_ST_ACCEL_I2C_3AXIS
which has unmet direct dependencies (IIO && !SENSORS_LIS3_I2C
&& IIO_ST_ACCEL_3AXIS && IIO_ST_SENSORS_I2C)
warning: (IIO_ST_ACCEL_3AXIS) selects IIO_ST_ACCEL_SPI_3AXIS
which has unmet direct dependencies (IIO && !SENSORS_LIS3_SPI
&& IIO_ST_ACCEL_3AXIS && IIO_ST_SENSORS_SPI)
(...)

This fixes the issue by putting the dependencies directly
in the top-level component instead, so that it never gets
to select its unselectable subcomponent.

Fixes: 76222772 ("iio: accel: st_accel: handle deprecated bindings")
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Jonathan Cameron <jic23@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>