Android build use different tool chain(gcc 4.9) with yocto(gcc 6.2),
'for' loop initial declarations are not supported in C90, define the
variable first before use it.

Test: build pass for imx8mm_evk.

Change-Id: Idf9a9f21626a02e2e679d2e74410378cd143c3f1
Signed-off-by: Luo Ji <ji.luo@nxp.com>