kernel: enable pressure interface

PSI provides a canonical way to see resource pressure increases as
they develop, with pressure metrics for three major resources:
memory, CPU, and IO. PSI stats are like barometers that provide
fair warning of impending resource shortages, enabling users to
take more proactive, granular, and nuanced steps when resources
start becoming scarce.

References:
* https://www.kernel.org/doc/html/latest/accounting/psi.html
* https://lwn.net/Articles/759781/

Build system: x86/64
Build-tested: x86/64/AMD Cezanne, flogic/glinet_gl-mt6000
Run-tested: x86/64/AMD Cezanne, flogic/glinet_gl-mt6000

Signed-off-by: John Audia <therealgraysky@proton.me>

target/linux/generic/config-6.6

@@ -4757,7 +4757,8 @@ CONFIG_PROC_SYSCTL=y
 # CONFIG_PSAMPLE is not set
 # CONFIG_PSB6970_PHY is not set
 # CONFIG_PSE_CONTROLLER is not set
-# CONFIG_PSI is not set
+CONFIG_PSI=y
+# CONFIG_PSI_DEFAULT_DISABLED is not set
 # CONFIG_PSTORE is not set
 # CONFIG_PSTORE_BLK is not set
 # CONFIG_PSTORE_COMPRESS is not set