lib: Add platform features in boot time print

We have now clear distinction between platform and hart features.
Modify the boot print messages to print platform features in a string
format. In the process, this patch moved relatively larger functions
to its own file from platform.h header file.

Signed-off-by: Atish Patra <atish.patra@wdc.com>
Tested-by: Jonathan Balkind <jbalkind@cs.princeton.edu>
Reviewed-by: Anup Patel <anup.patel@wdc.com>

lib/sbi/objects.mk

@@ -31,6 +31,7 @@ libsbi-objs-y += sbi_illegal_insn.o
 libsbi-objs-y += sbi_init.o
 libsbi-objs-y += sbi_ipi.o
 libsbi-objs-y += sbi_misaligned_ldst.o
+libsbi-objs-y += sbi_platform.o
 libsbi-objs-y += sbi_scratch.o
 libsbi-objs-y += sbi_string.o
 libsbi-objs-y += sbi_system.o