iio: accel: bma400: Fix a compilation problem

The kernel fails when compiling without `CONFIG_REGMAP_I2C` but with
`CONFIG_BMA400`.
```
ld: drivers/iio/accel/bma400_i2c.o: in function `bma400_i2c_probe':
bma400_i2c.c:(.text+0x23): undefined reference to `__devm_regmap_init_i2c'
```

Link: https://download.01.org/0day-ci/archive/20240131/202401311634.FE5CBVwe-lkp@intel.com/config
Fixes: 465c811f ("iio: accel: Add driver for the BMA400")
Fixes: 9bea1064

 ("iio: accel: bma400: add support for bma400 spi")
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Link: https://lore.kernel.org/r/20240131225246.14169-1-mario.limonciello@amd.com
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>