riscv: bitops: Use riscv_has_extension_likely

Use riscv_has_extension_likely() to check for RISCV_ISA_EXT_ZBB,
replacing the use of asm goto with ALTERNATIVE.

The "likely" variant is used to match the behavior of the original
implementation using ALTERNATIVE("j %l[legacy]", "nop", ...).

Signed-off-by: Vivian Wang <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Paul Walmsley <[e-mail]>

arch/riscv/include/asm/bitops.h

···
 
 static __always_inline __attribute_const__ unsigned long variable__ffs(unsigned long word)
 {
-	asm goto(ALTERNATIVE("j %l[legacy]", "nop", 0,
-				      RISCV_ISA_EXT_ZBB, 1)
-			  : : : : legacy);
+	if (!riscv_has_extension_likely(RISCV_ISA_EXT_ZBB))
+		return generic___ffs(word);
 
 	asm volatile (".option push\n"
 		      ".option arch,+zbb\n"
···
 		      : "=r" (word) : "r" (word) :);
 
 	return word;
-
-legacy:
-	return generic___ffs(word);
 }
 
 /**
···
 
 static __always_inline __attribute_const__ unsigned long variable__fls(unsigned long word)
 {
-	asm goto(ALTERNATIVE("j %l[legacy]", "nop", 0,
-				      RISCV_ISA_EXT_ZBB, 1)
-			  : : : : legacy);
+	if (!riscv_has_extension_likely(RISCV_ISA_EXT_ZBB))
+		return generic___fls(word);
 
 	asm volatile (".option push\n"
 		      ".option arch,+zbb\n"
···
 		      : "=r" (word) : "r" (word) :);
 
 	return BITS_PER_LONG - 1 - word;
-
-legacy:
-	return generic___fls(word);
 }
 
 /**
···
 
 static __always_inline __attribute_const__ int variable_ffs(int x)
 {
-	asm goto(ALTERNATIVE("j %l[legacy]", "nop", 0,
-				      RISCV_ISA_EXT_ZBB, 1)
-			  : : : : legacy);
+	if (!riscv_has_extension_likely(RISCV_ISA_EXT_ZBB))
+		return generic_ffs(x);
 
 	if (!x)
 		return 0;
···
 		      : "=r" (x) : "r" (x) :);
 
 	return x + 1;
-
-legacy:
-	return generic_ffs(x);
 }
 
 /**
···
 
 static __always_inline int variable_fls(unsigned int x)
 {
-	asm goto(ALTERNATIVE("j %l[legacy]", "nop", 0,
-				      RISCV_ISA_EXT_ZBB, 1)
-			  : : : : legacy);
+	if (!riscv_has_extension_likely(RISCV_ISA_EXT_ZBB))
+		return generic_fls(x);
 
 	if (!x)
 		return 0;
···
 		      : "=r" (x) : "r" (x) :);
 
 	return 32 - x;
-
-legacy:
-	return generic_fls(x);
 }
 
 /**