create a size variable for the sbi_hart_ext

On some platforms, e.g. coreboot, opensbi fails as the loop in
fdt_parse_isa_one_hart is for SBI_HART_EXT_MAX (32) items,
and the array is only 15 at present.

Create a variable, sbi_hart_ext_size, which can be used
in for loops and other conditionals.

Signed-off-by: Ronald G Minnich <rminnich@gmail.com>

Author: rminnich

include/sbi/sbi_hart.h

@@ -74,6 +74,7 @@ struct sbi_hart_ext_data {
 };
 
 extern const struct sbi_hart_ext_data sbi_hart_ext[];
+extern const int sbi_hart_ext_size;
 
 /*
  * Smepmp enforces access boundaries between M-mode and

lib/sbi/sbi_hart.c

@@ -668,6 +668,8 @@ const struct sbi_hart_ext_data sbi_hart_ext[] = {
 	__SBI_HART_EXT_DATA(smcdeleg, SBI_HART_EXT_SMCDELEG),
 };
 
+const int sbi_hart_ext_size = sizeof(sbi_hart_ext) / sizeof(sbi_hart_ext[0]);
+
 /**
  * Get the hart extensions in string format
  *

lib/utils/fdt/fdt_helper.c

@@ -401,7 +401,7 @@ static int fdt_parse_isa_one_hart(const char *isa, unsigned long *extensions)
 				continue;			\
 			}
 
-		for (j = 0; j < SBI_HART_EXT_MAX; j++) {
+		for (j = 0; j < sbi_hart_ext_size; j++) {
 			set_multi_letter_ext(sbi_hart_ext[j].name,
 					     sbi_hart_ext[j].id);
 		}