rt2800pci: fix comment about register access

Registers used for indirect BBP and RF registers access are
respectively BBPCSR and RFCSR, also make it clear that all CSR
registers access goes through rt2x00pci_register_[read,write]()
methods.

Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Acked-by: Ivo van Doorn <IvDoorn@gmail.com>
Acked-by: Gertjan van Wingerde <gwingerde@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/rt2x00/rt2800pci.c

@@ -56,8 +56,10 @@ MODULE_PARM_DESC(nohwcrypt, "Disable hardware encryption.");
 
 /*
  * Register access.
+ * All access to the CSR registers will go through the methods
+ * rt2x00pci_register_read and rt2x00pci_register_write.
  * BBP and RF register require indirect register access,
- * and use the CSR registers PHY_CSR3 and PHY_CSR4 to achieve this.
+ * and use the CSR registers BBPCSR and RFCSR to achieve this.
  * These indirect registers work with busy bits,
  * and we will try maximal REGISTER_BUSY_COUNT times to access
  * the register while taking a REGISTER_BUSY_DELAY us delay