LoongArch: Change 8 to 14 for LOONGARCH_MAX_{BRP,WRP}

LoongArch: Change 8 to 14 for LOONGARCH_MAX_{BRP,WRP}

The maximum number of load/store watchpoints and fetch instruction
watchpoints is 14 each according to LoongArch Reference Manual, so
change 8 to 14 for the related code.

Link: https://loongson.github.io/LoongArch-Documentation/LoongArch-Vol1-EN.html#control-and-status-registers-related-to-watchpoints
Cc: stable@vger.kernel.org
Fixes: edffa33c7bb5 ("LoongArch: Add hardware breakpoints/watchpoints support")
Reviewed-by: WANG Xuerui <git@xen0n.name>
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>