mwifiex: move debug_data dump function to common utililty file

mwifiex_debug_info also need be save to file when firmware dump happens.
Move its dump implementation function to commmon utilility file, thus it
can be reused in firmware dump function.

Signed-off-by: Xinming Hu <huxm@marvell.com>
Signed-off-by: Cathy Luo <cluo@marvell.com>
Signed-off-by: Avinash Patil <patila@marvell.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>