riscv: semihosting: correct alignment

Commit 7400d34b ("riscv: semihosting: replace inline assembly with
assembly file") reduced the alignment of function smh_trap().

As described in the "RISC-V Semihosting" specification [1] the ssli,
ebreak, and srai statements must all reside in the same memory page.

[1] RISC-V Semihosting, Version 0.4, 12th June 2024
    https://github.com/riscv-non-isa/riscv-semihosting



Fixes: 7400d34b ("riscv: semihosting: replace inline assembly with assembly file")
Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
Reviewed-by: Leo Yu-Chi Liang <ycliang@andestech.com>