Align the SBI function prototypes with SBI specification

[avpatel]

All existing SBI extensions are RV32 friendly so SBI CoVE extensions should also be RV32 friendly. Accordingly, the SBI spec recommends that physical address passed to SBI functions be split as separate "hi" and "lo" parameters because RV32 supports 34-bit wide physical address which is larger than XLEN and in the future, RV64 may support physical address wider than 64-bits (just like ARM world).