misc: apds990x: remove unused array ir_currents

Array ir_currents is declared but never used, hence it is redundant
and can be removed.

Cleans up clang warning:
warning: 'ir_currents' defined but not used [-Wunused-const-variable=]

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>