FP3: gpt-utils: Drop include for stdio.h

Required macros are already defined in kernel now, and due to use of
generated_kernel_headers, these gives conflict when compiled, hence drop
this include and use kernel side declaration

Test: libgptutils.fairphone_msm8953 compiles without any issues after this drop

Signed-off-by: Aayush Gupta <aayushgupta219@gmail.com>
Change-Id: I3edb0826bbac1dc2919bbb049b1e8956d0e1a8d7