soc: qcom: qti_battery_debug: Update QBG device context dump length

QBG device context dump length has been increased to 598 words in
the charger firmware. Increase the length to support upto 4KB.

Change-Id: I4a0a28044a54cdbde146101384f5a1ccf73b1562
Signed-off-by: Subbaraman Narayanamurthy <subbaram@codeaurora.org>