RISC-V: Remove duplicated include in smpboot.c

./arch/riscv/kernel/smpboot.c: asm/cpufeature.h is included more than once.

Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Closes: https://bugzilla.openanolis.cn/show_bug.cgi?id=7086


Signed-off-by: Yang Li <yang.lee@linux.alibaba.com>
Link: https://lore.kernel.org/r/20231031004018.45074-1-yang.lee@linux.alibaba.com


Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>