MIPS: Cleanup CP0 PRId and CP1 FPIR register access masks

Replace hardcoded CP0 PRId and CP1 FPIR register access masks throughout.
The change does not touch places that use shifted or partial masks.

Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/5838/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/sni/setup.c b/arch/mips/sni/setup.c
index 5b09b35..efad85c 100644
--- a/arch/mips/sni/setup.c
+++ b/arch/mips/sni/setup.c
@@ -25,6 +25,7 @@
 #endif
 
 #include <asm/bootinfo.h>
+#include <asm/cpu.h>
 #include <asm/io.h>
 #include <asm/reboot.h>
 #include <asm/sni.h>
@@ -173,7 +174,7 @@
 		system_type = "RM300-Cxx";
 		break;
 	case SNI_BRD_PCI_DESKTOP:
-		switch (read_c0_prid() & 0xff00) {
+		switch (read_c0_prid() & PRID_IMP_MASK) {
 		case PRID_IMP_R4600:
 		case PRID_IMP_R4700:
 			system_type = "RM200-C20";