LoongArch: Use "Exception return address" to comment ERA

The information contained in the comment for LOONGARCH_CSR_ERA is even
less informative than the macro itself, which can cause confusion for
junior developers. Let's use the full English term.

Signed-off-by: Yanteng Si <[email protected]>
Signed-off-by: Huacai Chen <[email protected]>

Author: Yanteng Si

arch/loongarch/include/asm/loongarch.h

@@ -250,7 +250,7 @@
 #define  CSR_ESTAT_IS_WIDTH		15
 #define  CSR_ESTAT_IS			(_ULCAST_(0x7fff) << CSR_ESTAT_IS_SHIFT)
 
-#define LOONGARCH_CSR_ERA		0x6	/* ERA */
+#define LOONGARCH_CSR_ERA		0x6	/* Exception return address */
 
 #define LOONGARCH_CSR_BADV		0x7	/* Bad virtual address */