spmi: pmic-arb: replace the writel_relaxed with __raw_writel

Replace the writel_relaxed with __raw_writel to avoid byte swapping
in pmic_arb_write_data() function. That way the code is independent
of the CPU endianness.

Fixes: 111a10bf ("spmi: pmic-arb: rename spmi_pmic_arb_dev to
spmi_pmic_arb")
Signed-off-by: Kiran Gunda <kgunda@codeaurora.org>
Reviewed-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>