max1720x_battery: update register read function

Some maxfg registers are not within 0x00 ~ 0xFF.
Ignore the unnecessary error message by replacing
REGMAP_READ with regmap_read

Bug: 203671196
Signed-off-by: Jenny Ho <hsiufangho@google.com>
Change-Id: I0cbbb0040d3806b9b1112e53fff2d2f66c172a61