bios_emulator: define the comment symbol for RISC-V assembler too

The bios_emulator driver cannot be compiled for RISC-V because the x86emu.h
header file doesn't define the comment symbol ("#") for the assembler.
With this patch, use the same symbol as for e.g. x86.

Signed-off-by: Yuri Zaporozhets <yuriz@qrv-systems.net>
diff --git a/drivers/bios_emulator/include/x86emu.h b/drivers/bios_emulator/include/x86emu.h
index d2650a8..cfdcd7b 100644
--- a/drivers/bios_emulator/include/x86emu.h
+++ b/drivers/bios_emulator/include/x86emu.h
@@ -54,7 +54,7 @@
 
 #if defined(CONFIG_ARM)
 #define GAS_LINE_COMMENT	"@"
-#elif defined(CONFIG_MIPS) || defined(CONFIG_PPC) || defined(CONFIG_X86)
+#elif defined(CONFIG_MIPS) || defined(CONFIG_PPC) || defined(CONFIG_X86) || defined(CONFIG_RISCV)
 #define GAS_LINE_COMMENT	"#"
 #elif defined (CONFIG_SH)
 #define GAS_LINE_COMMENT	"!"