x86/lib/msr: Clean up kernel-doc notation

Convert x86/lib/msr.c comments to kernel-doc notation to
eliminate kernel-doc warnings:

  msr.c:30: warning: This comment starts with '/**', but isn't \
  a kernel-doc comment. Refer Documentation/doc-guide/kernel-doc.rst
  ...

Fixes: 22085a66c2 ("x86: Add another set of MSR accessor functions")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/oe-kbuild-all/202304120048.v4uqUq9Q-lkp@intel.com/

arch/x86/lib/msr.c

@@ -27,14 +27,14 @@ void msrs_free(struct msr *msrs)
 EXPORT_SYMBOL(msrs_free);
 
 /**
- * Read an MSR with error handling
+ * msr_read - Read an MSR with error handling
- *
  * @msr: MSR to read
  * @m: value to read into
  *
  * It returns read data only on success, otherwise it doesn't change the output
  * argument @m.
  *
+ * Return: %0 for success, otherwise an error code
  */
 static int msr_read(u32 msr, struct msr *m)
 {
@@ -49,10 +49,12 @@ static int msr_read(u32 msr, struct msr *m)
 }
 
 /**
- * Write an MSR with error handling
+ * msr_write - Write an MSR with error handling
  *
  * @msr: MSR to write
  * @m: value to write
+ *
+ * Return: %0 for success, otherwise an error code
  */
 static int msr_write(u32 msr, struct msr *m)
 {
@@ -88,12 +90,14 @@ static inline int __flip_bit(u32 msr, u8 bit, bool set)
 }
 
 /**
- * Set @bit in a MSR @msr.
+ * msr_set_bit - Set @bit in a MSR @msr.
+ * @msr: MSR to write
+ * @bit: bit number to set
  *
- * Retval:
+ * Return:
- * < 0: An error was encountered.
+ * * < 0: An error was encountered.
- * = 0: Bit was already set.
+ * * = 0: Bit was already set.
- * > 0: Hardware accepted the MSR write.
+ * * > 0: Hardware accepted the MSR write.
  */
 int msr_set_bit(u32 msr, u8 bit)
 {
@@ -101,12 +105,14 @@ int msr_set_bit(u32 msr, u8 bit)
 }
 
 /**
- * Clear @bit in a MSR @msr.
+ * msr_clear_bit - Clear @bit in a MSR @msr.
+ * @msr: MSR to write
+ * @bit: bit number to clear
  *
- * Retval:
+ * Return:
- * < 0: An error was encountered.
+ * * < 0: An error was encountered.
- * = 0: Bit was already cleared.
+ * * = 0: Bit was already cleared.
- * > 0: Hardware accepted the MSR write.
+ * * > 0: Hardware accepted the MSR write.
  */
 int msr_clear_bit(u32 msr, u8 bit)
 {