[Change and sync linux version from OpenWRT]

[Description]
Change and sync linux version from OpenWRT
1. sync kernel to Openwrt21.02 : v5.4.188
2. sync mtk kernel patch from mtk_feed

[Release-log]
N/A

diff --git a/recipes-kernel/linux/linux-mediatek-5.4/generic/defconfig b/recipes-kernel/linux/linux-mediatek-5.4/generic/defconfig
index aba2911..73ba6af 100644
--- a/recipes-kernel/linux/linux-mediatek-5.4/generic/defconfig
+++ b/recipes-kernel/linux/linux-mediatek-5.4/generic/defconfig
@@ -652,6 +652,7 @@
 # CONFIG_BPFILTER is not set
 CONFIG_BPF_JIT=y
 # CONFIG_BPF_JIT_ALWAYS_ON is not set
+# CONFIG_BPF_UNPRIV_DEFAULT_OFF is not set
 # CONFIG_BPF_STREAM_PARSER is not set
 CONFIG_BPF_SYSCALL=y
 # CONFIG_BPQETHER is not set
@@ -1871,6 +1872,7 @@
 CONFIG_HARDENED_USERCOPY=y
 # CONFIG_HARDENED_USERCOPY_FALLBACK is not set
 # CONFIG_HARDENED_USERCOPY_PAGESPAN is not set
+CONFIG_HARDEN_BRANCH_HISTORY=y
 CONFIG_HARDEN_EL2_VECTORS=y
 # CONFIG_HARDLOCKUP_DETECTOR is not set
 # CONFIG_HAVE_AOUT is not set
@@ -3055,6 +3057,7 @@
 # CONFIG_MISDN_NETJET is not set
 # CONFIG_MISDN_SPEEDFAX is not set
 # CONFIG_MISDN_W6692 is not set
+CONFIG_MITIGATE_SPECTRE_BRANCH_HISTORY=y
 # CONFIG_MKISS is not set
 # CONFIG_MLX4_CORE is not set
 # CONFIG_MLX4_EN is not set
@@ -3315,7 +3318,6 @@
 # CONFIG_MTD_UIMAGE_SPLIT is not set
 # CONFIG_MTD_VIRT_CONCAT is not set
 # CONFIG_MTK_MMC is not set
-# CONFIG_MTK_SPI_NAND is not set
 CONFIG_MULTIUSER=y
 # CONFIG_MUTEX_SPIN_ON_OWNER is not set
 # CONFIG_MV643XX_ETH is not set
@@ -3813,7 +3815,6 @@
 # CONFIG_NLS_MAC_ROMANIAN is not set
 # CONFIG_NLS_MAC_TURKISH is not set
 # CONFIG_NLS_UTF8 is not set
-# CONFIG_NMBM is not set
 CONFIG_NMI_LOG_BUF_SHIFT=13
 # CONFIG_NOA1305 is not set
 # CONFIG_NOP_USB_XCEIV is not set