Documentation/kernel-parameters: Add riscv unaligned speed parameters

Document riscv parameters used to select scalar and vector unaligned
access speeds.

Signed-off-by: Andrew Jones <ajones@ventanamicro.com>
Link: https://lore.kernel.org/r/20250304120014.143628-18-ajones@ventanamicro.com
Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>

Author: jones-drew

Documentation/admin-guide/kernel-parameters.txt

@@ -7477,6 +7477,22 @@
 			Note that genuine overcurrent events won't be
 			reported either.
 
+	unaligned_scalar_speed=
+			[RISCV]
+			Format: {slow | fast | unsupported}
+			Allow skipping scalar unaligned access speed tests. This
+			is useful for testing alternative code paths and to skip
+			the tests in environments where they run too slowly. All
+			CPUs must have the same scalar unaligned access speed.
+
+	unaligned_vector_speed=
+			[RISCV]
+			Format: {slow | fast | unsupported}
+			Allow skipping vector unaligned access speed tests. This
+			is useful for testing alternative code paths and to skip
+			the tests in environments where they run too slowly. All
+			CPUs must have the same vector unaligned access speed.
+
 	unknown_nmi_panic
 			[X86] Cause panic on unknown NMI.