ARM: dts: qcom: msm8974-FP2: We're msm8974pro

Fairphone 2 always uses Snapdragon 801, a.k.a msm8974pro so change the
include and filename to that.

Signed-off-by: Luca Weiss <luca@z3ntu.xyz>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20220421211936.345168-1-luca@z3ntu.xyz