bus: mhi: host: Add a policy to enable image transfer via BHIe in PBL

Currently, MHI host only performs firmware transfer via BHI in PBL and
BHIe from SBL. To support BHIe transfer directly from PBL, a policy
needs to be added.

With this policy, BHIe will be used to transfer firmware in PBL if the
MHI controller has BHIe regs, sets seg_len, and does not set
fbc_download. The intention is to transfer firmware using BHIe in PBL
without further BHIe transfers in SBL.

Signed-off-by: Matthew Leung <quic_mattleun@quicinc.com>
Reviewed-by: Youssef Samir <quic_yabdulra@quicinc.com>
Reviewed-by: Jeffrey Hugo <quic_jhugo@quicinc.com>
Signed-off-by: Jeffrey Hugo <quic_jhugo@quicinc.com>
Reviewed-by: Jacek Lawrynowicz <jacek.lawrynowicz@linux.intel.com>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20250117170943.2643280-3-quic_jhugo@quicinc.com