max8903_charger: Allow platform data to be __initdata

Platform files may have declared 8903 platform data as __initdata. This
patch removes the dependency on pdata pointer so that using __initdata
on pdata will not incur errors. Note that such error does not incur
SECTION MISMATCH warning in (at least some) compilers.

Signed-off-by: MyungJoo Ham <myungjoo.ham@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Anton Vorontsov <cbouatmailru@gmail.com>