The driver goes to some length to dynamically allocate an array
to hold the channel addresses. However no ST sensor has more than
three channels (x, y, z at most). Instead of kmalloc():ing and
kfree():in the address array, just use a fixed array of three
elements.

Cc: Giuseppe Barba <giuseppe.barba@st.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Denis Ciocca <denis.ciocca@st.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>