power: supply: pmi8998_charger: rename to qcom_smbx

Prepare to add smb5 support by making variables and the file name more
generic. Also take the opportunity to remove the "_charger" suffix since
smb2 always refers to a charger.

Signed-off-by: Casey Connolly <casey.connolly@linaro.org>
Link: https://lore.kernel.org/r/20250619-smb2-smb5-support-v1-4-ac5dec51b6e1@linaro.org


Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>