lib: utils: Add detection of Smepmp from ISA string in FDT

- Add function to parse ISA string in FDT.
- Set Smepmp feature bit in extensions if "smepmp" string is found in ISA string.

Signed-off-by: Himanshu Chauhan <hchauhan@ventanamicro.com>
Reviewed-by: Anup Patel <anup@brainfault.org>

include/sbi_utils/fdt/fdt_helper.h

@@ -56,6 +56,9 @@ int fdt_parse_max_enabled_hart_id(void *fdt, u32 *max_hartid);
 
 int fdt_parse_timebase_frequency(void *fdt, unsigned long *freq);
 
+int fdt_parse_isa_extensions(void *fdt, unsigned int hard_id,
+			     unsigned long *extensions);
+
 int fdt_parse_gaisler_uart_node(void *fdt, int nodeoffset,
 				struct platform_uart_data *uart);